Cohen, who cut ties with Trump five years ago, will undergo more cross-examination by Trump’s lawyers, who are determined to undermine his credibility. Cohen testified yesterday that Trump “arbitrarily” inflated the value of the Trump Organization’s real estate assets to secure favourable insurance premiums.

Cohen said he doctored financial statements so the property values matched “whatever number Mr Trump told us.”

The insider testimony could bolster New York attorney-general Letitia James’ argument that Trump, his company, and several of its executives inflated property values. The case could break up Trump’s business empire.

Trump, the frontrunner for the 2024 Republican presidential nomination, has denied wrongdoing and defended the valuations of his properties, calling the case a “fraud” and a political witch hunt.

He and his lawyers have repeatedly called Cohen a “liar” and are likely to use his admitted history of deceit to challenge his testimony.

Cohen in 2018 pleaded guilty to a campaign finance violation and lying to Congress about Trump’s business dealings in Russia, which he testified yesterday that he did at Trump’s direction.

In about a half hour of cross-examination yesterday, Trump’s lawyer Alina Habba asked Cohen questions about the statement he gave in court in connection with his guilty plea to cast him as a convicted felon and serial liar.

Before the trial began on Oct 2, justice Arthur Engoron found that Trump fraudulently inflated his net worth and ordered the dissolution of companies that control crown jewels of his real estate portfolio, including the Trump Tower in Manhattan. That ruling is on hold while Trump appeals.

The trial largely concerns damages. James is seeking at least US$250 million in fines, a permanent ban against Trump and his sons Donald Jr and Eric from running businesses in New York, and a five-year commercial real estate ban against Trump and the Trump Organization.

Engoron last week fined Trump US$5,000 for violating a gag order.