Rapper Kid Cudi, the biggest star yet to take the witness stand in Sean "Diddy" Combs' trial, alleged that the rap mogul threatened him and was behind a Molotov cocktail attack that damaged his Porsche.

Cudi, whose legal name is Scott Mescudi, testified for about two hours on Thursday, answering questions about his relationship with Combs' ex-girlfriend Cassie Ventura, who testified last week.

The star told the court he also believed Combs was involved in a break-in at his home; later, Combs' lawyer emphasised that there was no evidence of Combs' involvement with either.

Mr Mescudi was among several witnesses who testified Thursday as the third week of the trial ended before the long Memorial Day weekend.

Combs is facing possible life in prison if convicted on charges of racketeering, sex trafficking and transportation to engage in prostitution. He has denied the charges and pleaded not guilty.

The rapper separately denied accusations in a barrage of civil lawsuits that echo some of the claims made in his criminal case.

"Are you in my house?"

Mr Mescudi told the court he and Ms Ventura dated for a few months in 2011 after Combs asked him to record music with her. Mr Mescudi testified about a series of incidents involving Combs.

The first happened in December 2011, when Mr Mescudi said he got a frantic call from Ms Ventura, who said Combs found out the two were seeing each other.

Mr Mescudi testified that he took Mrs Ventura to a hotel for safety, then got a call from a mutual friend, who said Combs and an another person were inside Mr Mescudi's Los Angeles home.

Mr Mescudi told the court he immediately got into his car and drove to his home, calling Combs on the way.

Combs answered the phone, he testified.

"(Expletive) are you in my house?" Mr Mescudi recalled asking Combs.

He alleged that Combs told him he wanted to talk and responded, "I'm over here waiting for you."

Mr Mescudi said he arrived at his home to find his security cameras facing the wrong way and unopened Christmas presents for his family rifled through. His dog also was locked in the bathroom and was acting "jittery and on edge".

He tried to call Combs again. "I wanted to confront him, I wanted to fight him," Mr Mescudi said on the stand.

He said he reported the incident to the police.

Mr Mescudi also told the court that shortly after his relationship with Ventura ended, in January 2012, his car was bombed with a Molotov cocktail.

Mr Mescudi testified that he got a call from his dog sitter who said his car was on fire. He told the court that he came home to find a hole cut in the roof of his Porsche and an explosive inside.

Prosecutors showed the jury photos of the interior of the car, which was charred.

Mr Mescudi accuses Combs of being behind the incident, though the mogul denied any involvement at a later meeting.

The jury also heard from makeup artist Mylah Morales, who told the court that she "feared for her life" after witnessing Mrs Ventura with a black eye, split lip and knots in her head on one occasion.

Frederic Zemmour, the general manager of a hotel where Combs often booked, also testified about deep cleaning after Combs stayed there.

The front desk noted that the guest "always spills candle wax on everything" and uses excessive amounts of oil.

When the trial resumes on Tuesday next week, the jury is expected to hear from Capricorn Clark, the woman who called Mr Mescudi when Combs was allegedly breaking into his home.