United States Secretary of State John Kerry
United States Secretary of State John KerryReuters

On the eve of a key meeting, United States Secretary of State John Kerry on Thursday made a powerful plea to the divided Syrian opposition to join landmark peace talks aimed at installing a new government.

Next week's peace conference in Switzerland was "the best opportunity for the opposition to achieve the goals of the Syrian people and the revolution," Kerry said in a surprise statement to reporters, according to the AFP news agency.

The Syrian opposition has yet to agree to sit down at the table with members of the Syrian regime of President Bashar Al-Assad to chart a path to end the war.

The UN-led peace conference, to be attended by some 35 countries, will open on January 22 in the Swiss city of Montreux, and then move to Geneva.

It will be the first time that the two sides have come together since the conflict erupted in March 2011, unleashing a brutal war which has claimed over 130,000 lives, and created millions of refugees.

The main political opposition body in exile, the Syrian National Coalition (SNC), has been plagued by internal bickering. It postponed a decision on whether to attend until next week after nearly a quarter of its 121 members threatened to resign following after the re-election of its Saudi-backed leader, Ahmad al-Jarba.

One of the groups in the opposition bloc, the Syrian National Council, recently reaffirmed it will not attend the talks. The group has long insisted that it refuses to negotiate until Assad’s regime exits power.

The Syrian regime has repeatedly said it will not attend a the Geneva peace conference if the aim is for Assad to hand over power.

Complicating the situation is the presence of extremist groups which flooded into Syria, leaving the more moderate American-backed opposition fighting both Assad's forces and Islamic terrorists.

Kerry, who only returned early Thursday from an overseas trip during which he attended a Syria donor's conference in Kuwait, stressed the U.S. was "deeply concerned about the rise of extremism."

"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," he warned.

The Syrian Opposition Coalition is due to vote Friday in Istanbul, and Kerry sought to allay their fears that the Geneva talks will somehow legitimize Assad's regime and leave him clinging to power.

The aim of the talks is to find a way to install a transitional government -- as agreed to in a June 2012 deal known as Geneva I.

The opposition can veto any names put forward for the transitional governing body, as does the regime, Kerry stressed.

"Any names put forward for leadership of Syria's transition must, according to the terms of Geneva I ... those names must be agreed to by both the opposition and the regime," he said, according to AFP.

"This means that any figure that is deemed unacceptable by either side, whether President Assad or a member of the opposition cannot be a part of the future," Kerry added.

Thursday's statement was just the latest bid by the U.S. administration to pressure the Syrian opposition to attend the conference, which has been in the planning since May.

The statement also comes amid reports that Western powers have reached out to Assad, who was commonly viewed as the “bad guy” in the conflict.

Syrian Deputy Foreign Minister Faisal Mekdad claimed in a televised interview Wednesday that several Western powers had approached the Assad’s forces to discuss "the extremism and cruelty" of the rebel forces, in the wake of reports that Syrian refugees were starving to death after being refused access to international aid. 

The West reaching out to Assad may be a direct result of the ongoing “second civil war” between the moderate rebels and the jihadists.

Three powerful rebel alliances – among them Islamist groups - have teamed up to fight the jihadist Islamist State of Iraq and the Levant (ISIS), which they have warned is worse than Assad’s regime.

The Al-Qaeda linked group has vowed to “crush” other rebel groups in Syria. The group’s growth has alarmed Western nations.

ISIS has been accused of several human rights abuses, including torturing and murdering prisoners, among them children and teenagers, and forcing Druze men to convert to Islam or die.