Standard and Poor's warned Monday it may cut Russia's debt rating in case of a drop in the price of oil because of its "huge impact" on the economy and president-elect Vladimir Putin's campaign promises.

The global ratings agency said a $10 decline in the global price of oil would lead to a 1.4-percent of gross domestic product drop in government revenues.

U.S. President Barack Obama said he and Russian counterpart Dmitry Medvedev agreed Monday to support diplomatic efforts to end the bloodshed in Syria and ensure a "legitimate" government there.

Syria was one of the top priority issues discussed during a 90-minute meeting between the two leaders in South Korea ahead of a nuclear summit, their final direct talks before Medvedev steps down and makes way for Vladimir Putin.

Russian President Dmitri Medvedev's Middle East envoy was in Algiers on Sunday for consultations on the deadly year-old crisis in Syria, a Russian diplomat said.

Mikhail Bogdanov, who arrived in the Algerian capital on Saturday, was holding talks with Foreign Minister Mourad Medelci, the APS news agency reported.

U.N.-Arab League envoy Kofi Annan's visit to China to discuss the crisis in Syria, initially scheduled for this weekend, will take place on Tuesday and Wednesday, the Chinese foreign ministry said.

Annan's spokesman had said on Friday he would visit Beijing and Moscow at the weekend for talks in two countries criticized for resisting global efforts to condemn Syrian President Bashar Assad.

The army resumed shelling the central Syrian protest cities of Homs and Hama on Saturday, monitors reported, as international envoy Kofi Annan headed to Russia in the latest push for peace.

Mortar shells rained down on the flashpoint Khaldiyeh district of Homs continuously for two hours in the morning, said the Syrian Observatory for Human Rights, adding that it had no information about casualties.

Progressive Socialist Party leader MP Walid Jumblat demanded on Friday that the ruling Assad family in Syria be removed from the country.

He said: “Anyone who believes that a settlement can be reached with the Assad family is crazy.”

Russian President Dmitry Medvedev on Friday cautioned against attempts to circumvent the authority of the United Nations as the West seeks to secure Moscow's support in the Syria crisis.

"There's a need to eliminate any loopholes allowing (nations) to act in circumvention of the authority of the Security Council and use force without its approval," Medvedev told a European security conference in Moscow.

U.N.-Arab League envoy Kofi Annan will travel this weekend to Moscow and Beijing to discuss the crisis in Syria, his spokesman said Friday, adding that a team sent to Damascus has returned.

The team is back after "three days of intensive talks with Syrian authorities on urgent steps to implement" Annan's proposals on halting the violence.

Police in the southern Russian province of Dagestan said Friday that a Muslim cleric, who criticized radical Islamists, has been killed by a powerful explosion.

Gitinmagomed Abdulgapurov, an imam in a mosque in the central city of Buinaksk, became the fifth Muslim cleric in the restive province killed in the past two years.

The U.N. Security Council on Wednesday adopted a presidential statement demanding that Syria "immediately" implement a peace plan proposed by U.N.-Arab League envoy Kofi Annan and giving a veiled warning of international measures.

The statement, which has less weight than a formal resolution, says the Council will "consider further steps as appropriate" if Annan reports that the Damascus government is not cooperating.