Russia is sending an anti-submarine ship and a missile cruiser to the Mediterranean, according to Russian news agency Interfax.

An armed forces source reportedly said the planned deployment was in response to the "well-known situation" - a clear reference to the conflict in Syria.

The navy has denied the deployment is linked to events in Syria, saying it is part of a planned rotation of its ships in the Mediterranean.

Russia is strongly against any military intervention in Syria, with Russian Foreign Minister Sergei Lavrov believing it would seriously destabilise the region.

Mr Lavrov has said any attack without UN Security Council approval would be a "crude violation" of international law.

The warship reports come after US President Barack Obama said the US had studied evidence and concluded that the Syrian government was behind the alleged attack.

Mr Obama said any strike would be to "send a shot across the bow" and give a "pretty strong signal that [Syria] better not do it again".

He added the US had not yet made a firm decision about how to respond, but that it could take action even without the backing of allies or the United Nations.

However, behind the scenes, US intelligence officials are reportedly saying the intelligence is no "slam dunk".

Questions are said to remain about who actually controls some of Syria's chemical weapons and whether President Assad himself explicitly ordered the alleged attack.

The Syrian leader was shown meeting Yemeni politicians on state television on Thursday.

It quoted President Assad as saying the country would defend itself in the face of any aggression.

A draft resolution by the UK on authorising a strike failed to win the approval of the UN Security Council on Wednesday as Russia reiterated its objections.

China has also entered the discussion and warned the West against any military action.

"China calls on all parties to exercise restraint and remain calm and to remain committed to the correct track of political solutions," Chinese Foreign Minister Wang Yi said.

British involvement in any strike will be debated today by politicians in the House of Commons.

Meanwhile, United Nations weapons inspectors set out on Thursday morning for the Damascus suburbs in a third day of investigations.

UN Secretary-General Ban Ki-moon has pleaded for all sides to hold off on any military strikes.

He said his inspection team would soon finish its investigation, leaving Syria on Friday and reporting their findings to him the following day.

Last week's alleged chemical attack is claimed to have killed 1,300 people.