Moscow: Both the government forces and rebels were responsible for the recent massacre in the Syrian town of Houla, Russian Foreign Minister Sergei Lavrov said.
"There can be no doubt that the authorities used artillery and tanks," Lavrov said after talks with his British counterpart William Hague in Moscow.
"Guilt should be apportioned objectively. It takes two to tango," he said.
Lavrov said "dozens of players" were involved in the current violence in Syria.
At least 108 people, around a third of them children, were killed on Saturday in Houla, near the former rebel stronghold city of Homs, according to UN observers.
The UN Security Council unanimously condemned the Syrian authorities over what it said was an "outrageous" attack. It made no mention of rebel forces.
"We are insisting on the carrying out of a probe into what happened in Houla. We need to understand how this happened to make sure it will never be repeated," Lavrov said.
Russian Deputy UN Ambassador Alexander Pankin said Moscow did not rule out that the killings in Houla were a "provocation" carried out by rebel forces ahead of a visit by UN peace envoy Kofi Annan to Syria on Tuesday. He also refused to rule out the participation of foreign special forces in the attack.
Hague said Britain accepted that rebel forces bore responsibility for some of the violence.
"We are not arguing that all violence in Syria is the responsibility of the Assad regime, although it has the primary responsibility for such violence," he said.
Both Hague and Lavrov insisted that Annan`s peace plan was the only way forward.
"We are very much agreed that the Annan plan is the best hope for Syria," Hague said.
Lavrov said Russia was applying pressure "daily" on Syria, but that it believed certain other countries were not fully committed to Annan`s plan.
"Russia has particular role in applying pressure," Lavrov said. "We sense from our contacts that some other forces are not committed. We support Kofi Annan`s plan and they should do everything for this to succeed. There should not be external interference."
Hague was keen to stress that Assad`s immediate fate was not the main concern.
"We have said all the way back from last August that finding a solution involves him standing aside," Hague said. "But the important thing is that the Annan plan is pursued. That is now the urgent priority."
Lavrov said the main thing for Moscow was not who was in power in Syria, but a successful implementation of Annan`s plan.
"The main thing is stopping the violence, and to create a political dialogue among the Syrian people. Everything else is secondary. And if we want to stop the violence, we have to work together with the regime and the opposition. Kofi Annan`s plan is about consensus," he said.
Over 9,000 people have been killed in clashes since the uprising against Assad began in March 2011, according to UN estimates.