Syrian opposition leaders will visit Moscow next week in what could be a litmus test for an agreement struck by the United States, Russia and other major powers on a plan for political transition in Syria.

“We will use this coming meeting with yet another Syrian opposition group to continue work to end violence and start Syrian dialogue between the government and all groups of the Syrian opposition as soon as possible,” Russian Foreign Minister Sergei Lavrov said yesterday.

All parties to Saturday’s Geneva agreement hailed the deal as “concrete progress” toward resolving the crisis, but there was no timeline for specific actions and no consensus on the key question of whether President Bashar Assad must step down.

The agreement brokered by international envoy Kofi Annan says a transitional governing body “shall be formed on the basis of mutual consent.” An earlier draft was watered down after Russia stonewalled, adamant that Assad should not be forced out.

As soon as it was agreed, both sides immediately disagreed about what the deal meant for Assad.

Russian Foreign Minister Sergei Lavrov said it did not imply at all that he should step down, but US Secretary of State Hillary Clinton said “Assad will still have to go.” French Foreign Minister Laurent Fabius said Assad was “finished,” while China’s Foreign Minister Yang Jiechi urged patience.

Assad himself said Syria would not accept anything imposed from outside. In an interview with Turkish media, published in full by Syria’s state news agency SANA yesterday, he stressed the importance of protecting Syria’s sovereignty and non-interference in its internal affairs.

“For us, what American officials say has no credibility in general,” he said.

“Second, the American position is already hostile to Syria in this crisis. They are part of the problem. They support the terrorists very clearly. That’s why we are not very interested in what this or that official says during this crisis.”

He added that if elections showed the Syrian people wanted him to step down, he would do so. Assad faces his next election in 2014 but, in a one-party state where elections are widely considered not to be free and fair, he is unlikely to face much of a challenge.

Asked about the deal at a UN briefing yesterday, Annan’s spokesman Ahmad Fawzi said there was agreement in principle on a political transition, which should not be underestimated.