Syria's opposition leader has rejected an invitation from Russia for peace talks, dealing another blow to hopes that diplomacy can be resurrected to end a 21-month civil war.
Russia, President Bashar al-Assad's main international protector, said it had sent an invitation to Moaz Alkhatib, whose National Coalition opposition group has been recognised by most Western and Arab states as the legitimate voice of the Syrian people.
But in an interview, Mr Alkhatib said he had already ruled out such a trip and wanted an apology from Moscow for its support for Mr Assad.
"We have clearly said we will not go to Moscow. We could meet in an Arab country if there was a clear agenda," he said.
"Now we also want an apology from (Russian Foreign Minister Sergei) Lavrov because all this time he said that the people will decide their destiny, without foreign intervention. Russia is intervening and meanwhile all these massacres of the Syrian people have happened, treated as if they were a picnic."
"If we don't represent the Syrian people, why do they invite us?" Mr Alkhatib said. "And if we do represent the Syrian people why doesn't Russia respond and issue a clear condemnation of the barbarity of the regime and make a clear call for Assad to step down?
"This is the basic condition for any negotiations."
With the rebels advancing steadily over the second half of 2012, diplomats have been searching for months for signs that Moscow's willingness to protect Mr Assad is faltering.
So far Russia has stuck to its position that rebels must negotiate with Mr Assad's government, which has ruled since his father seized power in a coup 42 years ago.
"I think a realistic and detailed assessment of the situation inside Syria will prompt reasonable opposition members to seek ways to start a political dialogue," Mr Lavrov said.
That was immediately dismissed by the opposition: "The coalition is ready for political talks with anyone ... but it will not negotiate with the Assad regime," spokesman Walid al-Bunni told Reuters.
"Everything can happen after the Assad regime and all its foundations have gone. After that we can sit down with all Syrians to set out the future."