Why FBI raid of Trump lawyer's office should leave president very worried, according to Fox News legal expert

Leader denounces move as 'disgraceful situation' and an 'attack on what we all stand for'

A Fox News legal analyst who has the ear of Donald Trump has explained why the FBI raid of Michael Cohen’s office should leave the president with significant cause for concern.

Mr Trump denounced the raid as a break-in and a “disgraceful situation” that was part of an “attack on what we all stand for” by special counsel Robert Mueller.

Agents carried out a search on Monday, seizing records on subjects reportedly including a $130,000 (£92,000) payment to adult actress Stormy Daniels, who claims she had sex with Mr Trump.

But Andrew Napolitano, a former New Jersey Superior Court judge, suggested it was the approval of the search warrants themselves that may spell the most trouble for the president and his lawyer.

Mr Napolitano told Fox News that under normal circumstances Mr Trump would receive attorney-client privilege over his communications with Mr Cohen, but that this would not apply “if there is a serious allegation of unlawful activity, by the lawyer with the client”.

“There must be some evidence presented to a federal judge here in New York City sufficient to persuade that judge to sign a search warrant to permit the FBI in broad daylight to raid an attorney’s office, particularly when that attorney has one client and it happens to be the president of the United States,” Mr Napolitano said.

“That evidence would have to be such as to persuade a neutral observer, the federal judge, that it is more likely than not, that among these seized documents is evidence of crimes by Mr Cohen or Mr Cohen and the president.”

On Tuesday morning, Mr Trump appeared to confirm his concern over the seizure of documents relating to his communications with Mr Cohen. He angrily tweeted "Attorney-client privilege is dead!", adding "A TOTAL WITCH HUNT!!!"

Mr Napolitano speculated that the payment to Stormy Daniels could be at the heart of the FBI raid.

“We know of course of the Stormy Daniels allegations, which is, where could this money have come from?” he said. “Would it be lawful if it didn’t come from Donald Trump? And if it came from Donald Trump, why did the president not acknowledge it?”

The former judge went on to reiterate the gravity of the situation, saying that for a federal judge to break attorney-client privilege, they must have “been satisfied that it’s more likely than not that in those materials are evidence of crimes”.

Mr Trump appears to respect Mr Napolitano's opinion and has repeatedly parroted them on Twitter. In February, the president quoted the legal analyst’s view that the Department of Justice had a “treasure trove” of evidence of criminality by Hillary Clinton.

He also echoed arguments Mr Napolitano made on Fox News condemning US government surveillance, and has reportedly met the Fox News employee on several occasions since becoming president.