The United States Tuesday pledged to release its intelligence findings into the Syria chemical attack this week, but said it was "preposterous" that anybody would blame anyone other than the Assad regime.

Underlining signals that an expected US military action would be of limited scope, the White House said it was not seeking to bring about "regime change" in Syria and refused to say whether it would seek a UN mandate to strike.

White House spokesman Jay Carney said there "should be no doubt, for anyone who approaches this logically, that the Syrian regime is responsible for the use of chemical weapons on August 21 outside Damascus."

"Suggestions that there is any doubt about who is responsible for this are as preposterous" as arguments that the attack did not take place, he said.

Carney's comments seemed to be a new US swipe at Syria's ally Russia, which has cast doubt on US claims that President Bashar al-Assad's regime was responsible for the horrific chemical attack on civilians last week which is believed to have killed hundreds of civilians.

While officials insist that President Barack Obama has yet to make a decision on how to respond the attack, there is near certainty in Washington that he will chose to launch a limited military strike against Syrian targets.

They argue, that after months trying to avoid being draw into another Middle East war, that their action is aimed purely at punishing Assad for the use of chemical weapons, which they say crossed international norms.

They say possible US action should not be seen as an intervention in the vicious civil war or an attempt to directly bring down the Assad regime.

We cannot let chemical weapons use go unpunished: British PM
London, England (AFP) Aug 27, 2013 - Any action against Syria would be aimed at "degrading" the regime's alleged chemical weapons' capability, British Prime Minister David Cameron said Tuesday.

After announcing that the British parliament would be recalled on Thursday to debate possible action, Cameron described the use of chemical weapons as "morally indefensible".

But any military action against Syria would have to be proportionate and legal, the prime minister said.

Cameron said no decisions had been taken but Britain and its allies had to consider whether targeted military action was required to "deter and degrade the future use of chemical weapons".

"This is not about wars in the Middle East; this is not even about the Syrian conflict. It's about the use of chemical weapons and making sure as a world we deter their use," he said.

"The question we need to ask is whether acting or not acting will make the use of chemical weapons more prevalent?"

Earlier, British Deputy Prime Minister Nick Clegg denied that the aim would be to topple the regime of President Bashar al-Assad.

"What we're considering is a serious response (to chemical weapons use)," he said.

"What we're not considering is regime change, trying to topple the Assad regime, trying to settle the civil war in Syria one way or another."

Britain, France and the United States have all said they believe the alleged gas attacks that killed hundreds of civilians near Damascus last week were launched by the regime.

US Defence Secretary Chuck Hagel said US forces were ready to launch strikes against the Syrian regime once President Barack Obama gave the order.

In Paris, French President Francois Hollande said his country was "ready to punish" those behind the alleged attacks.

British lawmakers will debate Syria on Thursday.

In tense scenes a decade ago, the House of Commons gave its approval to the invasion of Iraq by a comfortable margin in March 2003 when Tony Blair was prime minister.

Two years ago, they gave overwhelming support -- 557 to 13 -- to airstrikes to assist the Libyan rebel forces.

It is the fourth time Cameron has recalled parliament during a recess -- previously a rarely-used step. The last time was for a day of tributes to former prime minister Margaret Thatcher, who died in April.