US Secretary of State John Kerry has said president Bashar Assad could resolve the Syrian crisis by handing all his chemical weapons over to the international community by the end of the week.

In a strong rebuttal to remarks by Assad, Mr Kerry said there was compelling evidence that the Syrian regime used chemical weapons against its own people.

In an interview on CBS’s This Morning, Assad argued that the evidence Mr Kerry has disclosed about chemical weapons use amounts to a “big lie” that resembles the case for war in Iraq the US made to the United Nations over a decade ago.

Asked to respond, Mr Kerry said he would be confident to take evidence that the US intelligence committee has gathered into any court.

“What does he offer?” Mr Kerry asked. “Words that are contradicted by fact.”

Mr Kerry, in London for talks on the crisis, also said that the British Parliament’s decision against endorsing a military strike in Syria would not damage US-British relations. “Our bond is bigger than one vote – bigger than one moment in history,” he said.

He said the US realised that there was no military solution to the conflict, but that a political resolution will not be possible if the Assad regime is allowed to continue killing the Syrian people without consequences.

“The evidence is powerful and the question for all of us is what are we going to do? Turn our backs? Have a moment of silence?” he said.

Mr Kerry said Washington also “knows where the rockets came from and where they landed ... and it was no accident that they all came from regime -controlled territory and all landed” in opposition-held territory.

Meanwhile, Russian and Syrian foreign ministers said they planned to push for the return of United Nations inspectors to Syria to continue their probe into the use of chemical weapons.

Russia Sergey Lavrov said after talks with his Syrian counterpart Walid al-Moallem that Moscow will continue to promote a peaceful settlement and may try to convene a gathering of all Syrian opposition figures who are interested in peaceful settlement. He said a US attack on Syria would deal a fatal blow to peace efforts.