Russian investigators said Monday they were searching the homes of top protest leaders on the eve of a mass rally against President Vladimir Putin's rule.

The Investigative Committee said in a statement that the raids targeted Alexei Navalny as well as Ilya Yashin and Sergei Udaltsov over a previous rally "that ended in mass disturbances."

Russia will not approve the use of force against the Syrian regime at the United Nations, Foreign Minister Sergei Lavrov said Saturday at a briefing in Moscow.

"We will not sanction the use of force at the United Nations Security Council," Lavrov said in televised remarks as he gave a briefing on Russia's proposal for an international conference on Syria.

Russia on Saturday pushed its proposal for an international conference on Syria to include Iran, despite skepticism from the United States.

Russian Foreign Minister Sergei Lavrov was to give details on the plan for regional players to try to negotiate a strategy that would suit all Syrians at a briefing in Moscow at 1200 GMT.

The Syrian army killed at least 23 civilians in two protest cities on Saturday, a watchdog said, as an international outcry mounted over a massacre in a central village.

U.N. observers who visited the village of Al-Kubeir, near Hama, said they witnessed blood on the walls and "a strong stench of burnt flesh," prompting Western governments to launch a push for tough new sanctions against Damascus.

Russia's President Vladimir Putin on Friday said he had signed a controversial bill that sharply raises fines for opposition protesters despite pleas from rights activists to veto the law.

Russia said Friday after talks with U.S. Secretary of State Hillary Clinton's Syria envoy that it was unaware of any plans by President Bashar al-Assad to leave power.

Senior Russian diplomats said they also told special envoy Fred Hof that Moscow was willing to agree changes to international envoy Kofi Annan's peace plan for Syria as long as they kept the tattered initiative alive.

Russian Foreign Minister Sergei Lavrov Thursday vowed there would be no U.N. Security Council mandate for outside intervention in Syria, indicating Moscow would use its veto to block any military action.

"There will not be a Security Council mandate for outside intervention, I guarantee you that," Lavrov told reporters on the sidelines of a trip to Kazakhstan by President Vladimir Putin.

Russia on Thursday said a new massacre in Syria in which at least 55 civilians were reported killed was a provocation aimed at undermining the faltering peace plan of U.N.-Arab League envoy Kofi Annan.

"There is no question that certain forces, not for the first time, are using the most brutal and vile provocations to undermine the plan of Kofi Annan," Russian foreign ministry spokesman Alexander Lukashevich told a regular briefing in televised remarks, referring to the latest violence in Hama.

Russian President Vladimir Putin told his Iranian counterpart on Thursday that Moscow supports Tehran's atomic program as long as it is "peaceful".

"We have always supported the right of the Iranian people to modern technologies, including the peaceful use of atomic energy," he told Mahmoud Ahmadinejad on the sidelines of a regional security summit in Beijing.

U.S. Secretary of State Hillary Clinton said Wednesday she would reserve judgment on a Russian proposal for a global conference on Syria that would include Iran together with other powers.

"It's hard to imagine inviting a country (Iran) that is stage managing the Assad regime's assault on its people," she said at the end of a visit to Azerbaijan, referring to Syrian President Bashar al-Assad.