Donald Trump's former lawyer Michael Cohen has pleaded guilty to lying to the US Congress.

Mr Cohen made a surprise appearance in a New York courtroom this afternoon, after a charge was brought by special counsel Robert Mueller.

Mr Mueller is leading the investigation into alleged Russian interference in the 2016 presidential election.

Associated Press reports that Trump's former personal lawyer today admitted making false statements to Congress about work he did on a proposed Trump Tower project in Moscow.

Mr Cohen submitted written testimony to a Senate committee last year about the project.

In court documents published by The New York Times, the special counsel's office claims Mr Cohen "knowingly and willfully made a materially false, fictitious, and fraudulent statement and representation".

In brief comments to reporters outside court today, Mr Cohen's lawyer insisted that his client has "co-operated [and] will continue to co-operate".

Earlier this year, Mr Cohen pleaded guilty to eight criminal counts, including breaches of campaign finance law.

He's due to be sentenced next month over those charges.

The charges followed an investigation into his business dealings and his role in paying 'hush money' to women to stop negative stories about Donald Trump.

Mr Cohen has previously acknowledged paying the adult film actress Stormy Daniels - whose real name is Stephanie Clifford - $130,000 in return for her not speaking out about an alleged affair between herself and Mr Trump in 2006.