Trump ex-lawyer Cohen's help in Russia probe detailed in Mueller memo

US President Donald Trump's ex-lawyer has given substantial help on how Russian nationals tried to affect the 2016 election, a legal memo has revealed.

Michael Cohen's help is detailed in the memo from Robert Mueller, who is heading the probe into alleged Russian collusion with the Trump team, BBC reported on Saturday.

The memo is mainly to guide sentencing for crimes Cohen has admitted.

A second Mueller memo sets out the case against ex-campaign chief Paul Manafort for breaching a plea bargain deal.

Cohen and Manafort are among a number of Trump aides being investigated in Special Counsel Mueller's probe.

Both have been co-operating with his team but Mueller now accuses Manafort of lying.

In a separate court filing on Friday, prosecutors in New York made their case for the length of Cohen's sentence when it is delivered on Wednesday.

They say he should serve a "substantial" jail term after admitting violating campaign finance laws, committing tax evasion and lying to Congress.

President Trump has repeatedly denied there was any collusion with Russian officials, calling the investigation a "witch hunt".

The White House said Friday's memos offered nothing new or damaging about the president.

Trump tweeted: "Totally clears the President. Thank you!" although it was unclear to what he was referring.

Cohen had admitted making false statements about a Trump property deal, out of loyalty to the president.

The memo says that although this crime was serious, any sentencing should be served concurrently with the New York prosecutors' recommendations on other crimes.