Moscow has angrily rejected British accusations of top-level state involvement in the poisoning of a double agent in Salisbury.

Even the suggestion that the Kremlin could have been involved was "unacceptable," said Dmitry Peskov told journalists. "Neither the highest level, nor any lower ranks nor any official representatives had anything to do with the events in Salisbury."

On Wednesday, British Prime Minister Theresa May indicated that the operation to administer a nerve agent at the home of double agent Sergei Skripal was led by military intelligence, known commonly as GRU. It was, she said, "almost certainly approved ... at a senior level of the Russian state."

"This was ... not a rogue operation," she added.

Salisbury attack: Two Russian spies named as suspects in novichok poisoning case

On Thursday, security minister Ben Wallace went further, identifying Russian president Vladimir Putin as the man “ultimately responsible” for the attack.

“I don’t think anyone can ever say that Mr Putin isn’t in control of his state,” he told BBC Radio Four. “Of course he’s responsible, he’s leader of the state.”

Mr Peskov said that in order for Russia to take any measures to investigate the identities of the two men, the UK would need to send an official request to Moscow.

The spokesman seemed already to be aware of the official British position that it saw "no sense" in issuing an official warrant. In a statement on Wednesday, the Crown Prosecution Service said it would not be applying for extradition, citing a history of non-cooperation following similar requests.