London: British Prime Minister David Cameron has spoken to US President Barack Obama on phone against the backdrop of both countries considering military intervention in Syria, officials said on Wednesday.
Downing Street said Cameron heard the "latest on US thinking" on the issue, ahead of a National Security Council meeting today and a House of Commons vote on Thursday.
"No decision has yet been taken. Any action we take or others take would have to be legal, would have to be proportionate," Cameron said.
"It would have to be specifically to deter and degrade the future use of chemical weapons."
Cameron said he took his responsibilities "about safeguarding our armed services incredibly carefully, incredibly seriously".
"But the question we need to ask is whether acting or not acting will make the use of chemical weapons more prevalent," he added.
The Syrian government has blamed opposition fighters for an alleged chemical attack near Damascus on August 21, in which hundreds of people were reportedly killed.
The latest phone call between Obama and Cameron was the second since the alleged chemical attack.
Foreign Secretary William Hague, in an article published in The Daily Telegraph today, reiterated that Britain faces a choice between military strikes against Syria or allowing tyrants around the world to use chemical weapons "with impunity".
"According to the UN, the Syrian conflict is already the worst refugee crisis since the Rwandan genocide, creating nearly two million refugees and killing more than 100,000 people so far," he wrote.
"But it is now infamous for another, equally chilling reason: this is the first time that chemical warfare has been used anywhere in the world in the 21st century.
"The United Nations Security Council should rise to its responsibilities by condemning these events and calling for a robust international response," he added.
The British government is expected to publish the parliamentary motion for debate today, along with details of intelligence linking the Syrian government to the attack.
The motion is expected to stress the need for "appropriate measures" in response to the use of chemical weapons by any country.
Several Conservative backbenchers have raised concerns about military intervention in Syria, but it is understood Tory MPs will be told to support the measures.
The US has said its forces are "ready to go" but former British military chiefs warned a one-off missile strike could see the UK dragged into deeper action.
The UK`s Stop the War Coalition, which led protests against the Iraq war, called on the public to oppose what it called "another disastrous military intervention". It is planning to hold a protest at Downing Street.