Usa news: He says Michael Cohen breached his duty as attorney to act in his client’s best interests.

The lawsuit comes amid escalating attacks from Trump allies on Cohen, who is a key witness in a New York investigation into the ex-president.

A Manhattan prosecutor last week charged Mr Trump with fraud in relation to hush money payments to a porn star.

Cohen’s spokesman and lawyer, Lanny Davis, told the BBC he was confident the lawsuit against his client would fail.

The legal action, filed in a Florida federal court, also accuses Cohen of making “improper, self-serving, and malicious statements about his former client, his family members, and his business”.

Cohen worked as Mr Trump’s attorney for over a decade. He was also a vice-president at the Trump Organization, and was often described as Mr Trump’s fixer.

But the two had a major falling out after the 2016 election, as investigators began looking into several of Mr Trump’s aides.

In 2018, Cohen was sentenced to three years in prison and a fine after pleading guilty to charges of fraud and campaign finance violations.

Now out of prison, Cohen has become a high-profile critic of Mr Trump, and a frequent guest on news programmes.

He has written a book and hosts a podcast, both of which Mr Trump cites in the lawsuit.

Cohen’s lawyer, Mr Davis, said in a statement to the BBC: “Mr Trump appears once again to be using and abusing the judicial system as a form of harassment and intimidation against Michael Cohen.

“It appears he is terrified by his looming legal perils and is attempting to send a message to other potential witnesses who are co-operating with prosecutors against him.”