Mr Kerry accused the Syrian regime of ‘systematically destroying evidence’ The use of chemical weapons in Syria is “a moral obscenity” and the West will “stand up to assure there is accountability”, John Kerry said today as he delivered the strongest indication yet of imminent military intervention.

The US secretary of state made clear America held the Syrian government responsible for both the “cowardly crime” and the “cynical attempt to cover it up” and promised further action would be announced within days.

“President Obama believes there must be accountability for those who would use the world’s most heinous weapons against the world’s most vulnerable people,” Mr Kerry said. “Nothing today is more serious, and nothing is receiving more serious scrutiny. Mr Kerry did not announce specific steps but said the Obama administration was working closely with both Congress and foreign leaders to coordinate action.

He accused the Syrian regime of “systematically destroying evidence” at the scene of the attack which killed more than 350 people in a Damascus suburb last week.

“That is not the behaviour of a government that has nothing to hide,” he said, adding that the regime’s “belated decision to allow access is too late to and is too late to be credible”.

Mr Kerry said the US would not wait for the report of UN inspectors on the ground in Syria but would be “informed by conscience and guided by common sense”.

He hinted at US intelligence reports confirming the Assad regime’s guilt, saying America had “additional information about this attack” which would be made public “in the days ahead”.

“We know that the Syrian regime maintains custody of these chemical weapons. We know that the Syrian regime has the capacity to do this with rockets. We know that the regime has been determined to clear the opposition from those very places where the attacks took place. And with our own eyes, we have all of us become witnesses,” he said.

Jay Carney, the White House press secretary, said it was “undeniable” that chemical weapons had been used and that there was “very little doubt” that the Assad regime was responsible.

Mr Kerry did not say whether the US would seek approval from the United Nations Security Council before launching any potential attack.

In an unusually passionate address at the State Department, Mr Kerry said he had watched “gut-wrenching” online videos of the bodies of the victims.

“I can’t get the image out of my head of a man who held up his dead child, wailing while chaos swirled around him, the images of entire families dead in their beds without a drop of blood or even a visible wound, bodies contorting in spasms, human suffering that we can never ignore or forget,” he said.

Mr Kerry said the levels of casualties and the reports of humanitarian groups on the ground “strongly indicate that everything these images are already screaming at us is real, that chemical weapons were used in Syria.”

Although the was in Syria has already claimed more than 100,000 lives, Mr Kerry said the illegal use of chemical weapons went “beyond the conflict in Syria itself”.

“This is about the large-scale indiscriminate use of weapons that the civilized world long ago decided must never be used at all, a conviction shared even by countries that agree on little else,” he said.

The emphasis on deterring the Assad regime from further use of chemical weapons was echoed by Mr Carney at the White House press briefing.

“This use of chemical weapons is distinct because it so clearly violates an international norm that has been in place for a very, very long time,” he said.