The United States expressed deep skepticism about suggestions by Syria's deputy prime minister that the regime was open to discussing Syrian President Bashar al-Assad's resignation.

"We saw the reports of the press conference that the deputy prime minister gave. Frankly, we didn't see anything terribly new there," State Department spokeswoman Victoria Nuland said.

Deputy Prime Minister Qadri Jamil said after talks in Moscow Tuesday that Syria was ready to discuss anything in negotiations -- even Assad's resignation.

The surprise comments emerged after Russia warned the West against meddling in Syria in the wake of US President Barack Obama's warning to Damascus over its chemical weapons arsenal.

"As far as his resignation goes -- making the resignation itself a condition for holding dialogue means that you will never be able to reach this dialogue," he said.

But Jamil added: "Any problems can be discussed during negotiations. We are even ready to discuss this issue."

The United States has said for the past several weeks that it wants to speed Assad's departure.

"The Syrian government knows what it needs to do, and the Russian government, as you know, joined us in Geneva in setting forth a very clear transition plan," Nuland said.

She added the Russians should encourage the Assad regime "to start now to be following through on a transition plan, but, you know, there's no need to complicate it, as the deputy prime minister appeared to do there."

"Obviously, the longer this goes on, the harder it is, but we still believe that the faster Assad goes, the more chance there is to quickly move on to the day after," she said.

According to political sources in Damascus, Jamil was sent to Moscow to discuss a possible plan for presidential elections in Syria in which all candidates would be allowed to stand, including Assad.

The exiled opposition umbrella group the Syrian National Council said it was studying the formation of a transitional government, but did not elaborate on whether it could include regime figures.

The West has long demanded Assad's departure, accusing him of butchering his own people during a 17-month conflict that began as a peaceful uprising but has deteriorated into a brutal fight between regime forces and armed rebels.

Syria's traditional allies Russia and China have blocked UN resolutions on the conflict, rejecting what they see as foreign attempts at regime change.

Activists say more than 23,000 people have been killed since March 2011, while the UN puts the death toll at 17,000 and says hundreds of thousands more have fled or been made homeless in a major humanitarian crisis.

Syrian forces have killed dozens of civilians in a raid on a Damascus suburb, a watchdog said on Wednesday, reporting that many of the victims were summarily executed and others killed at a funeral.

At least 198 people reported dead across Syria on Tuesday, the Syrian Observatory for Human Rights said it has documented the names of at least 42 civilians killed when regime forces stormed Maadamiyat al-Sham.

However, dozens more are feared dead in the mixed suburb, which is home to about 200,000 people including Christians, Alawites and Sunni Muslims and lies to the west of Damascus.

"Initial reports say that the army targeted a funeral procession, killing at least 36 people," the Britain-based watchdog said, adding that it is working to document the victims' names.

The Observatory also said that dozens of unidentified bodies had been found in a basement in Maadamiyat al-Sham on Tuesday, the latest grisly find as the 17-month conflict becomes increasingly brutal.

It is impossible to verify the claims.

Shelling by regime forces and fighting in the northern city of Aleppo on Tuesday also killed at least 31 civilians, including five women and five children, said the group, which has a network of monitors on the ground.

More than 23,000 people have been killed in Syria since the outbreak of an anti-regime revolt in March last year, according to the Observatory. The UN puts the death toll at 17,000.