President Donald Trump is with the UK "all the way" over the poisoning of former spy Sergei Skripal, according to a spokesperson for British Prime Minister Theresa May.

The US president has been hesitant to blame Russia for the attack even as the UK government said it was "highly likely" the country was behind it.



President Donald Trump has told British Prime Minister Theresa May that the US is with the UK "all the way" over the poisoning of ex-spy Sergei Skripal and that Russia must provide "unambiguous answers" over the use of nerve agent in the attack, according to a Number 10 spokesperson.

The UK prime minister spoke to the US president on Tuesday about the incident, which has left Skripal and his daughter Yulia critically ill and sent relations between the UK and Russia plummeting.

While May has said it is "highly likely" that the Russian government is behind the nerve gas attack, the White House has been more reticent about attribution. In a press briefing on Monday, White House press secretary Sarah Huckabee Sanders declined to say whether the US endorsed the UK's view that Russia is responsible or to condemn Russia by name.

"As soon as we get the facts straight, if we agree with them, we will condemn Russia or whoever it may be," Trump said earlier on Tuesday.

A May spokesperson described Tuesday's call in a statement.

"The Prime Minister set out the conclusion reached by the UK Government that it was highly likely that Russia was responsible for the attack against Sergei and Yulia Skripal," according to the statement.

"President Trump said the US was with the UK all the way, agreeing that the Russian Government must provide unambiguous answers as to how this nerve agent came to be used."

The White House echoed this in a statement Tuesday, noting, "President Trump agreed with Prime Minister May that the Government of the Russian Federation must provide unambiguous answers regarding how this chemical weapon, developed in Russia, came to be used in the United Kingdom."

Russia has repeatedly denied any involvement in the attack.

May has set a deadline of midnight UK time on Tuesday for Russia to explain how Novichok nerve agent — a family of poisons developed by Russia during the Cold War — came to be used on Sergei Skripal. Russia says it will not respond to the "ultimatum" unless it is provided with samples of the nerve gas.