Although a unified opposition movement failed to emerge after a two-day conference in Cairo under the auspices of the Arab League, one message rang loud and clear from assembled anti-government groups - Syria's transitional period can begin only after Assad is no longer in the picture.

"When Assad and the main symbols of his regime are removed, changes will happen," Anas Abdah, a member of the Syria National Council, told ABC News. "For the first time, we have all main opposition groups present, and I can say with certainty, no one even put a request for modification of this point."

International diplomats, including the Turkish Foreign Minister, representatives from Iraq, Kuwait and Qatar, and prominent Syrian businessmen and independent politicians also attended the conference. The first day was mostly dedicated to reviewing the "Transitional Period" document - an agreement outlined by the Syria Action Group at a meeting in Geneva last Saturday, that pledged to implement an interim government to prevent escalating violence in the region.

"The bloodshed must end, and the parties must be prepared to put forward effective interlocutors to work with me towards a Syrian-led settlement," Kofi Annan, the Arab League and UN special envoy, said on Saturday.

"This conference is part of a series of meetings," Abdah said. "Like when in Istanbul two weeks ago we prepared a committee, like Geneva, and it will be part of what happens in Paris in a few days."

But two key representatives, one international and one local, were absent from Cairo.

Russia, Syria's main ally along with China, was not in attendance, but Foreign Minister Sergei Lavrov said in a statement on Tuesday that he would meet Syrian opposition leaders in Moscow next week to discuss the possibility of ending violence in the country.

Lavrov was quoted in Russia Today as saying : "Unfortunately, some representatives of the Syrian opposition began to state that the Geneva decisions are unacceptable for them," adding: "Some Western participants in the meeting began to distort the agreements ."

Russia will also be absent from the upcoming Friends of Syria meeting in Paris on Friday, which seeks to co-ordinate Western and Arab efforts to stop the violence in the country, French Foreign Minister Laurent Fabius told members of the press.

From within the Syrian opposition movement, members of the Free Syria Army declined to take part in Cairo talks.

"They are cautious and skeptical - they think politicians are going to create a conspiracy. I think they were not happy with the level of participation they were given," Abdah said.

"The 'political solutions' will not guarantee the dismantling of the security forces working under the Assad regime. The people will not consent on having such a government - and we will not give up on the demands of the people," Col. Qasem Saad Aldeen, head of the Military Council in Homs and its suburbs, told ABC.

"The document was not clear enough, as each foreign minister spoke of the document in a different way, meaning that none of the countries agree on it," Aldeen said. "It is obviously just a means to give more time for Bashar al-Assad to continue butchering the Syrian people."

Aldeen is currently based in Rastan, a suburb of Homs. He described how the city and its surrounding areas are daily subjected to heavy shelling from "tanks, warplanes, and rocket bombardment."

"This shelling proves that the regime has completely lost control over the areas it is bombarding," Aldeen said. "The escalation of the violence leads to the defections against the regime's army; therefore, the regime savagely retaliates by bombarding areas as it completely loses control over them."

Escalating violence invites increased scrutiny of the situation in Syria, particularly from international monitors such as the United Nations and Human Rights Watch.

UN High Commissioner for Human Rights Navi Pillay renewed her call on Monday on the Security Council to refer the situation in Syria to the International Criminal Court, which recently marked its 10-year anniversary.

Speaking to the press in New York, Pillay said: "Those responsible for attacks against civilians must be held accountable. … I believe that the evidence points to the commission of crimes against humanity."

The United Nations estimates that more than 10,000 people, mostly civilians, have been killed in Syria and tens of thousands displaced since the anti-government uprising began 16 months ago. The London-based Syrian Observatory for Human Rights reported a higher figure of 16,500. The watchdog reported more than 50 Syrian deaths on Tuesday.

"Since the first day of the revolution, the regime has set its plan clearly. They killed everyone they were capable of killing in the protests; they also arrested everyone they were able to arrest and executed thousands of civilians," Aldeen said.

It emerged today that one way the Assad regime has been targeting opposition activists and protestors, is torture.

A new report published by the New York-based Human Rights Watch organization compiled a year's worth of undercover investigations by local activists, and detailed 27 functioning torture centers across Syria.

"The material published today presents a very chilling account of systematic torture," David Mepham, the UK Director of Human Rights Watch, told ABC News. "People are burnt with acid, they're raped, they're subject to mock executions, they have electricity put through their bodies; I mean, the most extraordinary things happen to people in these centers."

Mepham explained how, through extensive and careful research, Human Rights Watch mapped the location of each center, as well as the names of the people running them. All the information is listed on the organization's website.

"They're scattered, there's a network of these centers, but they're largely run by different branches of the Syrian intelligence services," Mepham said.

NATO Secretary-General Anders Fogh Rasmussen on Monday called the situation in Syria "one of the gravest security challenges the world faces today," according to The Associated Press.

Following the publication of the Human Rights Watch report, top diplomats of France and Germany echoed opposition groups like the Syria National Council meeting in Cairo, saying that Assad should step down.

The UN-brokered plan left the question of whether Assad will step down undecided. According to High Commissioner Pillay, "Ending the conflict is what we all seek."

But opposition leaders like Abdah said that disagreements over how to end it was the root of the problem for the opposition, as well as for the international community.

"I am cautiously optimistic, but the main problem even in this conference, is that some delegates are asking us to come up with some kind of liaison group to speak on behalf of all the opposition. That has not been agreed upon so far," he said.

As concern over the threat of sectarian violence rises, the issue of weapons and arms control is becoming paramount.

"Russia and Iran are supplying the Syrian regime with weapons like helicopters and ammunition for tanks," Lord David Hannay, a former ambassador to the UN and Chair of the UN All-Party Parliamentary Group, told ABC as the UN Arms Trade Treaty Conference kicked off Tuesday in New York.

Hannay said the conference was the result of a "very long process" in arms control negotiations: "The UN is now bringing all members together to see if they can actually agree on a treaty to set out rules in a way that will reduce the flow of illegal weapons and make governments consider very carefully any arms export, bearing in mind human rights and conflict issues."

But Hannay added that, even if for the first time a set of rules was agreed upon to regulate international arms trade - valued at more than $60 billion a year - it would remain in the hands of each government to "decide its own procedures."

Speaking about the possible effect of the treaty on Syria, Hannay said: "It wouldn't bring an arms embargo. Only the UN Security Council can do that, and so far there hasn't been one." He called the conference "an important building block."

In the meantime, arms continue to flow into Syria - from Russia, for the Assad regime, and according to the Free Syria Army, some of these weapons eventually find their way into rebel's hands.

"Most of our weapons are gained during the defection of the soldiers," Aldeen said. "During the operations targeting military bases, some arms are plundered and a small fraction of the weapons are actually brought from the regime's militias themselves as some of the regime's personnel do not believe or have faith in what they are doing - they sell their own weapons for money.

"We surely will not back down or surrender until all those who have butchered the unarmed, innocent people in Syria be prosecuted," he said. "And the first on our list is Bashar Al Assad and those closely related to him."