Russian Foreign Minister Sergeiy Lavrov, right, greets Syria's Deputy Foreign Minister Fayssal Al-Mekdad, during their meeting in Moscow on May 22, 2013. (Mikhail Metzel/AP)

Russia said Friday that the government of Syrian President Bashar al-Assad has agreed “in principle” to participate in a peace conference sponsored by Russia and the United States.

“Confirmation of the Syrian government’s tentative readiness to take part in the international conference on Syria has been received from Damascus,” Foreign Ministry spokesman Alexander Lukashevich said at a news briefing.

It was the first indication that Assad’s government intends to participate in the conference, for which a date has yet to be set.

“The Syrian government has shown a constructive approach,” Lukashevich said. He added, however, that Moscow doubts whether representatives of the Syrian opposition will join the talks.

“They are again using a precondition of President Bashar al-Assad’s resignation and propose forming some ‘government’ under the U.N. aegis,” he said. “Generally speaking, they are doing everything possible to dilute the idea of the conference and cancel the principles of the Geneva communique.” The United States, Russia and other countries met in Geneva in June 2012 and issued a call for a negotiated settlement of the Syrian conflict.

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The Syrian Opposition Coalition expressed skepticism about Friday’s announcement.

“We’d expect this to come out of Damascus, not Moscow,” said spokesman Louay Safi, as coalition members met in Istanbul to decide whether to attend the peace talks. “There is a lack of clarity. What does ‘in principle’ mean? Assad himself needs to say he wants to engage in negotiations and that he is willing to do what it takes for a transition to democracy and transfer of powers.”

Coalition members have said the group will attend only if Assad’s ouster is the goal of any transition plan. Assad has made clear that his departure will be decided by elections, which are scheduled for 2014.

The former head of the opposition coalition, Mouaz al-Khatib, has put forward a 16-point peace plan under which Assad would hand power to his prime minister or deputy and step aside with 500 others. It has received limited backing from the divided opposition, but Safi said elements of it may be adopted.

The coalition’s Western and Arab backers have struggled to unite the group — which has been rudderless since Khatib resigned in March — ahead of the U.S.- and Russian-brokered peace talks. A new leader is expected to be elected Saturday.

Russia, with China’s support, has blocked U.N. action on Syria. Russian President Vladimir Putin reportedly fears an outcome similar to that in the Libyan conflict, with NATO powers intervening militarily against a sovereign government. Russia argues that Assad’s departure would open the way for Islamic radicals to take power in Damascus, and it has continued to sell weapons to Syria despite Western denunciations.

The United States and Western European countries have demanded that Assad step down, but during a recent visit to Moscow, Secretary of State John F. Kerry appeared to back away from that insistence, provided peace talks can begin. On Wednesday, the United States joined with European and Arab countries in saying that Assad must step down before a transitional government can assume power in Syria.

Kerry also promised broader support for the rebels if diplomacy fails.

A senior State Department official said Friday that Kerry will meet with Foreign Minister Sergei Lavrov on Monday in Paris to continue discussions from their meeting in Russia.

Putin’s spokesman, Yuri Ushakov, said Friday in Sochi that the president has been in touch with interested leaders from several countries about Syria. Russia’s stance on the conflict is subject to refinement as events warrant, he said in remarks relayed by the Interfax news agency, “but the pillars of this stance remain the same.”

Morris reported from Beirut. Anne Gearan contributed to this report from Tel Aviv.