Secretary of State John Kerry urged a Western-backed but deeply divided Syrian opposition group to put aside its concerns and participate in peace talks next week.

"On the eve of the Syrian Opposition Coalition General Assembly meeting tomorrow to decide whether to participate in Geneva, in the peace conference, the United States, for these reasons, urges a positive vote," Kerry said in a short, last-minute statement in the State Department briefing room.

The Syrian National Coalition, which will decide Friday and Saturday whether it wants to participate in the Geneva II talks Jan. 22, has thus far not agreed on much because of internal divisions, as the group is comprised of varied religious and cultural blocs that don't share the same ideologies.

While not a perfect group, it is one of the few rebel organizations to have the blessing of the United States, so its absence would mean a significantly smaller voice for anti-Assad Syrians in the talks.

Kerry also criticized vaguely people seeking to "muddy the waters" as to the goal of the talks in Geneva, and reiterated that the purpose is to get Syrian President Bashar al-Assad to step down and to find a transition government acceptable to both the opposition and the regime.

Syrian Foreign Minister Walid al-Muallem reportedly sent a letter to U.N. Secretary General Ban Ki-Moon saying the regime will attend Geneva II next week on the condition that countries stop supporting "terrorist groups" in the region.

"We demand the countries supporting terrorism cease and refrain from funding, training, arming or harbouring terrorist groups in harmony with international law and UN resolutions," al-Muallem said, according to Al Jazeera.

Also on Wednesday, Syrian Deputy Foreign Minister Faisal Mekdad claimed in an interview with the BBC that Western intelligence officials are holding meetings in Damascus with the regime to discuss combating Islamist radicals.

"Of course some are waiting for Geneva, some are saying we are exploring the possibilities, some are saying we want to co-operate on security measures because those terrorists they are sending from Western Europe into Turkey, into Syria, have become a real threat to them," Mekdad said.

"We of course refute" that suggestion, a State Department official said.

In his remarks today, Kerry questioned why the U.S. would want to work with the Assad regime to rid the country of actual terrorist groups like the al-Qaeda-linked al-Nusra Front, which are a powerful presence in the region.

"The world needs no reminder that Syria has become the magnet for jihadists and extremists. It is the strongest magnet for terror of any place today," Kerry said. "So it defies logic to imagine that those whose brutality created this magnet - how they could ever lead Syria away from extremism and towards a better future is beyond any kind of logic or common sense."

In an email to ABC News, the Syrian National Coalition said Kerry should worry himself not with the Coalition's participation, but with the regime's statements, which a spokesperson said "refused the principal bases on which Geneva II is based."

"The Coalition has repeatedly reiterated their willingness to participate in a successful political, peaceful transition that will establish democracy in Syria. The current conditions do not show any promises in that regard," the spokesperson continued.