The US government has imposed economic sanctions as punishment for the Novichok poisonings in Wiltshire.

And the furious Kremlin has vowed to respond.

The US State Department, Washington's equivalent of the British Foreign Office, said the new sanctions would go into effect this month.

Intelligence agencies in the US now believe that the attack on Sergei Skripal and his daughter Yulia were made by Russian agents

It accused President Vladimir Putin's government of having used "chemical or biological weapons in violation of international law" in the poisoning.

President Putin's spokesman Dmitry Peskov said the sanctions were “absolutely unlawful and don’t conform to international law and added:“No proofs, no clues, no logic, no presumption of innocence, just highly-likelies. Only one rule: blame everything on Russia, no matter how absurd and fake it is. Let us welcome the United Sanctions of America!”

The British government was reported to be on the brink of requesting the extradition from Russia of two of its citizens police here believe were responsible for the attack.

While the Skripals have recovered after weeks in hospital Wiltshire woman Dawn Sturgess was killed by the deadly nerve agent after she and her partner Charlie Rowley came into contact with it, possibly contained in a perfume bottle in Amesbury.

Mr Rowley has also been released form hospital after intensive care.

Investigations continue.