Theresa May has accused Moscow of "insulting the public's intelligence" after the two Russian agents suspected carrying out of the Salisbury poisonings claimed they were merely tourists.

In an extraordinary interview with state-funded news channel RT, Alexander Petrov and Ruslan Boshirov said they made a weekend visit to Britain to see Salisbury cathedral and were victims of a "fantastical coincidence".

The two men broke cover a day after after Vladimir Putin insisted they were "civilians" and told them to tell their story, a move that one senior government source said put the Russian president “directly in the frame”.

Downing Street dismissed their account as "lies and blatant fabrications" which would be "deeply offensive" to the victims of the chemical weapons attack on Salisbury and their families.

The Prime Minister's spokesman also accused Russia of responding "with contempt" to the murder of Dawn Sturgess and the attempted murders of former Russian spy Sergei Skripal and his daughter Yulia, and of Ms Sturgess's partner Charlie Rowley.

"Sadly, it is what we have come to expect" from Russia, the spokesman added.