Donald Trump "arbitrarily" inflated the value of his properties on financial statements, the former president's fraud trial in New York has heard.

His former lawyer, Michael Cohen, told the court he helped come up with "whatever number Trump told us to" on the real estate assets.

Cohen, a fixer-turned-foe of Mr Trump, is a key witness in the trial.

The judge has already ruled that Mr Trump inflated the value of his properties to secure favourable loans.

In addition to this civil trial, the former president is battling four criminal cases while he campaigns for the White House.

On the witness stand in the Manhattan court on Tuesday, Cohen said one of his responsibilities was to "reverse engineer" assets to increase their value based on a number "arbitrarily elected" by Mr Trump.

He said he and former Trump Organization finance chief Allen Weisselberg would work until they reached their boss's "desired goal".

Cohen also said Mr Trump had tried to use financial documents with inflated assets in his unsuccessful 2014 bid to buy the Buffalo Bills, a National Football League team.

Mr Trump sat with a stony face and folded arms as Cohen entered the court.

He appeared to look in his now-disbarred former attorney's direction as he took the stand, but said nothing.

As the court recessed for lunch, Mr Trump told reporters that Cohen was "not a credible witness".

The Republican front-runner for the 2024 presidential election denied any wrongdoing as he arrived at court earlier.

Mr Trump has been occasionally attending the trial on a voluntary basis and is expected to testify himself at some point.

Cohen - who once stated he would "take a bullet" for Mr Trump - was handed a three-year jail sentence in 2018 for lying to Congress and over hush payments he made on Mr Trump's behalf.

As he arrived at court, Cohen told reporters: "This is about accountability, plain and simple."

His testimony marked the first time the two have been in the same room in five years.

"Heck of a reunion," he said during the court break.

Cohen's testimony to Congress in 2019, when he said Mr Trump had inflated his property values, sparked the New York fraud investigation led by New York Attorney General Letitia James.

Ms James, a Democrat and the state's top prosecutor, is seeking a fine of $250m (£205m) and a ban on Mr Trump doing business in his home state.

In late September, the judge, Arthur Engoron, ruled Mr Trump had committed fraud through repeatedly misrepresenting his wealth by hundreds of millions of dollars.

Judge Engoron ordered that a court-appointed receiver take over companies that operate Trump Tower and other crown jewels of the ex-US president's real estate portfolio. An appeals court has blocked that move for now.

The judge also fined the former president $5,000 last week for failing to remove an online post mocking a court clerk - in contravention of a gag order.

Mr Trump does not face the risk of prison as a result of this civil trial, although the judge has threatened him with jail if he breaks the court-imposed order again.

He has repeatedly denied any wrongdoing, arguing that his assets were actually undervalued.

Mr Trump has also previously sued Cohen, accusing him of "spreading falsehoods" and breaking a confidentiality agreement.

That lawsuit was halted earlier this month, but a Trump spokesperson said it would be refiled at a later date.