MOSCOW - Syria is ready for talks with its armed opponents, Foreign Minister Walid al-Moualem said on Monday, in the clearest offer yet to negotiate with rebels fighting President Bashar al-Assad.

But Moualem said at the same time Syria would pursue its fight "against terrorism", alluding to the conflict in which the United Nations says 70,000 people have been killed.

His offer of talks drew a dismissive response from US Secretary of State John Kerry, who was starting a nine-nation tour of European and Arab capitals in London.

"It seems to me that it's pretty hard to understand how, when you see the Scuds falling on the innocent people of Aleppo, it is possible to take their notion that they are ready to have a dialogue very seriously," Kerry said.

He said US President Barack Obama was evaluating more steps to "fulfil our obligation to innocent people", without giving details or saying whether Washington was reconsidering whether to arm the rebels, an option it has previously rejected.

"We are determined that the Syrian opposition is not going to be dangling in the wind," Kerry said.

Obama has carefully avoided deeper US involvement in Syria, at the heart of a volatile Middle East, as he has withdrawn troops from Iraq and extracts them from Afghanistan.

Assad and his foes are locked in a bloody stalemate after nearly two years of combat, destruction and civilian suffering that threatens to destabilise neighbouring countries.

Syria's Moualem said in Moscow that Damascus was ready for dialogue with everyone who wants it, even with those who have weapons in their hands "because we believe that reforms will not come through bloodshed but only through dialogue".

"WAR AGAINST TERRORISM"

Russia's Itar-Tass, which reported his remarks, did not say if Moualem had attached any conditions for the dialogue.

"What's happening in Syria is a war against terrorism," the agency quoted him as saying. "We will strongly adhere to a peaceful course and continue to fight against terrorism."

Moaz Alkhatib, head of the opposition Syrian National Coalition, told reporters in Cairo he had not been in touch with Damascus following Moualem's offer. "We have not been in contact yet, and we are waiting for communication with them," he said.

Syria's government and the political opposition have both suggested in recent weeks they are prepared for some contacts - softening their previous outright rejection of talks to resolve a conflict which has driven nearly a million Syrians out of the country and left millions more homeless and hungry.

The opposition says any solution must involve the removal of Assad, whose family has ruled Syria since 1970. Disparate rebel fighters, who do not answer to Alkhatib or other politicians in exile, insist Assad must go before any talks start.    

Brigadier Selim Idris, a rebel military commander, told Al Arabiya television that a ceasefire, Assad's exit, and the trial of his security and military chiefs must precede any talks.

Damascus has rejected any preconditions and the two sides also differ on the location for any talks, with the opposition saying they should be abroad or in rebel-held parts of Syria, while the government says they must be in territory it controls.

"STATE COLLAPSE"

Russian Foreign Minister Sergei Lavrov expressed alarm about events in Syria, which he said was at a crossroads.

"There are those who have set a course for further bloodshed and an escalation of conflict. This is fraught with the risk of the collapse of the Syrian state and society," he said.

"But there are also reasonable forces that increasingly acutely understand the need for the swiftest possible start of talks ... In these conditions the need for the Syrian leadership to continue to consistently advocate the start of dialogue, and not allow provocations to prevail, is strongly increasing."

Lavrov's warning that the Syrian state could founder appeared aimed to show that Russia is pressing Assad's government to seek a negotiated solution while continuing to lay much of the blame for the persistent violence on his opponents.

Russia has distanced itself from Assad and has stepped up its calls for dialogue as his prospects of retaining power have decreased, but insists that his exit must not be a precondition.

A deputy to Lavrov said the West had not matched Moscow's peace efforts. "Our Western partners ... have to some degree encouraged (the opposition) to continue the armed fight," Itar-Tass quoted Deputy Foreign Minister Gennady Gatilov as saying.

The Syrian National Coalition said on Friday it was willing to negotiate a peace deal, but insisted Assad could not be party to it - a demand that the president looks sure to reject.

UN envoy Lakhdar Brahimi has said Assad had told him he would complete his term in 2014 and then run for re-election.

International deadlock over how to bridge the political chasm between Assad and his opponents has allowed an increasingly sectarian conflict to rage on for 23 months.

Assad, announcing plans last month for a national dialogue, said it would exclude "traitors" and "puppets made by the West".

Kerry is to meet Lavrov in Berlin on Tuesday, but a senior US official said he expected no breakthrough on Syria there.

The new secretary of state is also to meet Syrian opposition leaders at a "Friends of Syria" conference in Rome on Thursday.

The Syrian National Coalition said on Monday it would attend the Rome meeting, reversing a decision it made last week to stay away in protest at Syrian government missile strikes on Aleppo.

The change of mind came after Kerry called Alkhatib to urge him to attend.

"I want our friends in the Syrian opposition council to know we are not coming to Rome simply to talk. We're coming to Rome to make the decision about next steps," Kerry said earlier.