DOMINIC Cummings kept audio recordings of key conversations in government, an ally has claimed.

The Prime Minister's former chief adviser is locked in an explosive war of words with Boris Johnson after Downing Street accused him of a string of damaging leaks.

No 10 attempted to rubbish his claims on Friday night, saying it was not true that the Prime Minister had discussed ending a leak inquiry after a friend of his fiancee Carrie Symonds was identified as the likely suspect.

But an ally of Cummings said the PM's former chief aide took important material with him when he left Downing Street last year, including audio recordings of discussions with senior ministers and officials.

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"Dom has stuff on tape," the ally told the Daily Mail. "They are mad to pick a fight with him because he will be able to back up a lot of his claims.

"He used to tell advisers to record things all the time – discussions with officials. He has also kept a lot of his correspondence."

A Whitehall source yesterday said officials did not know the full extent of the material Cummings has. He has denied leaking and has already told MPs that aspects of the Government's approach to Covid went "catastrophically wrong".

Cummings is expected to use a select committee appearance before MPs next month to criticise his former boss for failures that have given Britain the worst death tolls in Europe.

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Over the weekend, Cummings launched a fresh attack on the Prime Minister, suggesting the Government had been too slow to shut the borders when the pandemic began.

The former No 10 aide, who is seeking an urgent parliamentary inquiry into the response to the pandemic, appeared to criticise ministers for failing to introduce travel bans for more than nine months after the virus came to Britain.

He tweeted that this was a “very important issue re learning from the disaster”, in response to a thread pointing at how Vietnam had insulated itself and limited its death toll to just 35.

No 10 aides fear that Cummings has nothing to lose in his battle. “Dominic has copies of everything and knows where all the bodies are buried,” an ally of Cummings told the Sunday Times.

According to the latest figures from the World Health Organisation (WHO), 127,417 people in the UK have died from Covid, the highest number in Europe.

Italy has the second-highest death toll of 119,021 and in France the death toll is 102,031, according to the WHO.

In Germany and Spain 81,564 and 77,496 people have died respectively.