A mortar shell has landed in the compound of the Russian embassy in central Damascus, injuring three people, the Russian Foreign Ministry said.

"On September 22 as a result of shelling by the rebels of the Damascus neighbourhood of Mazzeh, one of the shells exploded on the territory of the Russian embassy in Syria," the ministry said in a statement on Sunday.

"Three employees received non-life threatening injuries. Right now an investigation of the incident is under way."

The statement did not say whether those hurt were Russian or local employees, but it added that the embassy was looking into additional security measures after the attack.

Rebels fighting to overthrow Syria's President Bashar al-Assad have launched several mortar and rocket attacks in recent months into the centre of the Syrian capital, where many embassies and senior Syrian officials are based.

The Russian mission was damaged in February when a car bomb exploded nearby on a busy Damascus highway, killing 50 people.

No one was wounded at the embassy, but that blast blew out windows in the building, Russian officials said.

Sunday's embassy attack comes on the same day that Russia criticised what it said were Western attempts to use a Syrian chemical arms disarmament deal to seek a UN resolution threatening force against Assad's government.

"They see in the US-Russian deal not a chance to save the planet from significant quantities of chemical weapons in Syria, but as a chance to do what Russia and China will not allow, namely to push through a resolution involving [the threat of] force against the regime and shielding the opposition," Interfax news agency cited Sergey Lavrov, foreign minister, as saying.

Lavrov also said Russia, which has used its veto to block Western efforts to use the UN Security Council's clout to pressure Assad's government, was ready to send troops to Syria to ensure the safety of UN chemical weapons inspectors.

Geneva conference

Meanwhile, the president of the opposition Syrian National Coalition, Ahmad Jarba, said on Sunday that he was willing to attend a proposed Geneva conference to end two and a half years of conflict in Syria if it aims to establish a transitional government with full powers.

In a letter to the United Nations Security Council, obtained by Reuters and dated September 19, Jarba said the coalition "reaffirms its willingness to engage in a future Geneva Conference" but "all parties must ... agree that the purpose of the conference will be the establishment of a transitional government with full executive powers" as stipulated by an agreement last year by international powers.

It was the first clear commitment by the Western-and-Arab-backed coalition to attend the proposed conference sponsored by the United States and Russia.

The coalition has been dithering on whether to attend, especially after a chemical weapons attack on August 21 that killed hundreds of people in Damascus.