Former US president Donald Trump criticised the federal investigation into Rudy Giuliani and said he had no idea what US agents were looking for when they searched his former personal lawyer's Manhattan apartment and office.

In this file image, former New York City Mayor Rudy Giuliani, next to US President Donald Trump, delivers remarks to the City of New York Police Benevolent Association at Trump National Golf Club in Bedminster, New Jersey, US, August 14, 2020.
In this file image, former New York City Mayor Rudy Giuliani, next to US President Donald Trump, delivers remarks to the City of New York Police Benevolent Association at Trump National Golf Club in Bedminster, New Jersey, US, August 14, 2020. (Reuters Archive)

Former US leader Donald Trump has complained that an FBI raid on his ex-personal lawyer Rudy Giuliani's home was "so unfair," as President Joe Biden defended the integrity of the investigation, saying he had not been involved in the move against New York's one-time mayor.

Under Trump's turbulent presidency, he frequently accused US government institutions of playing political favourites but also used the power of his office to try to bend them to his will.

In this case, federal investigators with search warrants combed Giuliani's Manhattan residence and a separate office on Wednesday, seizing electronic devices as part of a probe into his dealings in Ukraine.

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"Rudy Giuliani is a great patriot. He just loves this country, and they raid his apartment," Trump told Fox Business on Thursday.

"It's very, very unfair. Rudy is a patriot who loves this country, and I don't know what they're looking for, what they're doing."

Giuliani's son Andrew Giuliani condemned the raid and accused the Justice Department of a political agenda. But Biden told NBC he had not even been warned a warrant had been obtained.

"I made a pledge I would not interfere in any way, order or try to stop any investigation the Justice Department had... I had no idea this was underway," he said.

"This last administration politicised the justice department so badly," he added.

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Giuliani legal woes

Giuliani, himself once a top New York prosecutor and before becoming a celebrated mayor of the city, was a personal lawyer for Trump when the president was impeached in December 2019 for seeking political help from Ukraine.

Giuliani spent months trying to help Trump find dirt in Ukraine on election rival Joe Biden and Biden's son Hunter, during 2018-2020.

But the investigation behind Wednesday's raid could be honing in on Giuliani doing paid work for Ukrainian businessmen at the same time, violating US laws against unregistered lobbying for foreign entities.

Two Ukrainian-born men, Lev Parnas and Igor Fruman, who helped Giuliani in those efforts, were arrested in October 2019 and charged with illegally funnelling large donations to a pro-Trump fundraising committee.

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Search warrants for Giuliani's phones

According to reports, the FBI and the Justice Department's prosecutor in New York had sought search warrants for Giuliani's phones last year, but were denied that while Trump remained in office, until January 20.

The FBI and Justice Department have declined to comment on the raids or the investigation.

Giuliani has other legal woes too. In January he was sued by a voting machine maker for $1.3 billion for spreading claims after the November presidential election that its machines were part of alleged massive voting fraud that caused Trump's loss.

No significant fraud has been demonstrated in the election.

Source: AFP