BEIRUT -- Syria's main opposition bloc wants to consult its allies before deciding on joining a U.S.-Russia initiative to negotiate a peaceful transition in Syria, its leader said Monday.
The U.S. and Russia called last week for an international conference to start talks that would be accompanied by a cease-fire. The two nations are on opposite sides of the Syria conflict, and this marks their first serious attempt at Syria diplomacy in a year.
The time, venue and agenda of the conference have not been set, reflecting disagreements between the two warring sides in Syria that scuttled previous initiatives.
Both have agreed in principle to attend, but the opposition Syrian National Coalition says it will not negotiate unless President Bashar Assad steps down first, while the regime has been vague about a truce.
George Sabra, head of the SNC, said Monday his coalition wants to consult with its allies, including Turkey, Saudi Arabia and Qatar, before making a decision.
"It is still early to make a decision on attending the conference," Sabra told reporters in Istanbul, Turkey. "It still has no agenda, program and list of attendees."
Even so, it appeared unlikely the opposition would refuse to take part, especially if its regional allies back the conference. U.S. diplomats have met with Arab leaders to ensure the opposition will eventually get on board.
Work on the logistics is under way.
Arab League chief Nabil Elaraby said over the weekend that Syria has given its list of attendees to its ally Russia. There was no immediate Syrian government comment.
Elaraby said the international envoy to Syria, Lakhdar Brahimi, is working on the setting up the conference, but no date has been set. Initially, the U.S. and Russia said it should be held by the end of the month.
The uprising against Assad erupted in March 2011 and escalated into a civil war. More than 70,000 Syrians have been killed and millions displaced.
Western leaders face growing pressure to find a way to end the conflict -- both because of the steadily rising death toll and fears that neighboring Turkey, Lebanon or Israel could get pulled deeper into it.
Turkey has blamed the Assad regime for twin car bombs Saturday that killed 46 people and wounded scores in a Turkish border town that serves as a hub for Syrian refugees and rebels.
Turkish Prime Minister Recep Tayyip Erdogan said Monday that Syria was behind the attacks "with certainty." He said Turkey is not ruling out retaliation but will act with caution and avoid being drawn into the civil war.
Syria has vehemently denied Turkey's accusations. There has been no claim of responsibility for the blasts in the town of Reyhanli.
On another front, Israel attacked suspected shipments of advanced Iranian missiles in Syria with back-to-back airstrikes this month. Israeli officials signaled there would be more attacks unless Syria refrains from trying to deliver such "game-changing" missiles to ally Hezbollah, an anti-Israel militia in Lebanon. Hezbollah responded by saying weapons shipments won't cease.
For now, the West is placing its hopes on the revived U.S.-Russian diplomatic initiative. Similar efforts ran aground in the past but now appear to have stronger Russian backing.
Through the conflict, Russia has sided with Assad, sending him weapons and shielding him against Western attempts to impose international sanctions.
British Prime Minister David Cameron suggested en route to a meeting with President Barack Obama that Russia is ready to find common ground with the West. Cameron met last week with Russian President Vladimir Putin to discuss the Syria initiative.
Cameron said late Sunday that there was a recognition by Putin "that it would be in all our interests to secure a safe and secure Syria with a democratic and pluralist future, and end the regional instability."
In fighting in Syria, regime troops have taken full control of the strategic town of Khirbet Ghazaleh, near the highway linking the capital Damascus with Jordan, according to the Britain-based Syrian Observatory for Human Rights, an activist group.
Rebels withdrew from the area after several days of fighting. Government forces conducted house-to-house searches Monday, the group said.
Troops also reopened the highway, restoring the supply line between Damascus and the contested provincial capital of Daraa, said Rami Abdul-Rahman, the head of the Observatory.
Rebels have been trying to carve a pathway from the Jordanian border through the southern province of Daraa, in what is seen as their best shot at capturing Damascus. A few weeks ago, they scored significant gains, but have since suffered setbacks in a government counteroffensive.
Arab officials and Western military experts have said Mideast powers opposed to Assad have stepped up weapons supplies to the rebels, with Jordan opening up as a new route.