BEIRUT -- Syrian troops on Monday captured five small villages and a hill on the edge of the northwestern province of Idlib, the last major rebel stronghold in the country, pro-government media said.
The extremist leader of the main rebel group in the region released a video calling on every able person to "perform his religious duty" and join the fight.
The pro-government Syrian Central Military Media said government forces captured the villages of Hawash, Jabrieh, Tawbeh, Sheikh Idriss, Jub Suleiman and Hawash hill on the southern edges of Idlib. The villages are near the strategic village of Kfar Nabuda, which Syrian troops entered last week.
Abu Mohammed al-Golani, leader of the al-Qaida-linked Hayat Tahrir al-Sham, or HTS, claimed in a video interview with a local activist that government troops suffered many losses while trying to advance into rebel-held areas over the past few days. Dressed in military uniform and holding an automatic rifle while seated under a tree, he claimed his militant group was gaining more fighters each day.
Al-Golani also said insurgents have the right to strike at a Russian base in Syria because "more than 90 percent of the Russian airstrikes are targeting women and children."
Syrian troops have been advancing on the rebels for nearly two weeks under the cover of Syrian and Russian airstrikes. In turn, the rebels have been blamed for firing rockets into Russia's air base in the nearby coastal province of Latakia.
Russia joined Syria's war in 2015, tipping the balance of power in favor for President Bashar Assad's forces. Opposition activists say Russian warplanes have been bombarding rebel-held areas intensely in recent weeks.
Much of Idlib is controlled by HTS, the largest and most powerful group in the area. Most of its fighters belonged to al-Qaida's affiliate in Syria, formerly known as the Nusra Front.
The United Nations said it was "alarmed by the ongoing reports of violence and hostilities in northwestern Syria, resulting in at least 100 civilians dead or injured and more than 180,000 displaced since the end of April."
U.N. deputy spokesman Farhan Haq said at U.N. headquarters in New York that the United Nations reiterated its call on all parties to protect civilians "at all costs," to stop destroying hospitals, schools and other civilian infrastructure, and to fulfill their obligations under international humanitarian and human rights laws.
He said that in the past two weeks, 18 health facilities had reportedly been struck, including 11 in Hama, six in Idlib and one in Aleppo governorates. He said at least four health workers had been killed. "At least 17 schools and three internally displaced settlements have reportedly been affected as well," Haq added.
France, Germany and Britain issued a joint statement calling for an end to the escalation of violence in northwestern Syria between government forces and HTS and "other terrorist groups."
The three European nations said that the presence of extremist groups in Idlib "remains of grave concern," but said the current Syrian advance "is not about fighting terrorism. It is about pushing forward the ruthless reconquest by the regime."
"We urge all the parties to avoid any military offensive in the region," the joint statement said.
The capture of more territory by Syrian troops comes as part of the latest push by government forces against the rebel-held enclave. So far, dozens have been killed and more than 150,000 have been displaced. Idlib is home to some 3 million people, many of them internally displaced from other parts of the country.
Opposition activists also reported government airstrikes and shelling of different areas in Idlib.
Syrian state media reported that insurgents fired rockets into the Christian government-held town of Suqailabiyah, killing one person and wounding five. The shelling came a day after a rocket attack on the town killed five children and a woman.
Associated Press writers Geir Moulson in Berlin and Edith M. Lederer at the United Nations contributed to this report.