Chinese actress Zhang Ziyi is suing a US-based Chinese online news outlet over claims that she was a prostitute who had sex with top official Bo Xilai and others, a lawyer said Wednesday.

The "Crouching Tiger, Hidden Dragon" star is taking legal action for libel in Los Angeles over the claims by Boxun News, which is based in North Carolina and offers Chinese- and English-language news online.

"At the heart of all of the claims are a series of libelous defamatory statements printed by Boxun News about Zhang Ziyi," attorney Adam LeBerthon, of the law firm representing the actress, told AFP.

"Boxun News printed repeatedly that Zhang Ziyi is a prostitute, and that's the heart of our allegations. She does not know (Bo), has not met him and has nothing whatsoever to do with him."

The lawsuit, obtained by AFP, said Boxun News claimed that Zhang earned over $100 million for having sex with Chinese officials and others, in news reports in May and June this year which were republished by media around the world.

"But none of the underlying reports are true, and Boxun News never had any legitimate basis to publish them. It never contacted Ms Zhang before it published the reports to confirm any of the alleged 'facts," it noted.

The US lawsuit came after Zhang launched legal action in June against Hong Kong's leading newspaper the Apple Daily and its sister weekly Next Magazine over reports that she prostituted herself with senior Chinese officials.

An article in Apple Daily on May 29 said Zhang "is a prostitute" and had sex with Bo and his wealthy associate Xu Ming for money on "numerous occasions," the court document said.

Attempts to get reaction from Boxun News were unsuccessful. A telephone number given on its website did not work.

The next court hearing in the Los Angeles case is scheduled for October 16, followed by another on November 16, but no trial date has yet been set. LeBerthon said the actress will likely not attend the pre-trial hearings.

"She will certainly be there at the time of trial, (although) the parties typically do not various pre-trial hearings," he added. "I don't expect Ms Zhang Ziyi to be any different."

Bo was sacked from his post as boss of Chongqing city in March and then suspended from China's powerful central politburo for "serious discipline violation" -- code for corruption.

Chinese authorities said late last month that Bo will "face justice" for a litany of crimes, including alleged abuse of power, taking bribes and improper sexual relations.

His wife, Gu Kailai, was handed a suspended death sentence for murder in August, after she was found guilty of murdering British businessman Neil Heywood, a crime she had confessed to, according to court officials.

The developments were the latest turn in a scandal that has rocked the Communist Party ahead of a once-a-decade power transition, with the party opening a pivotal congress to select new leadership on November 8.

Boxun News was founded in 2000, its website says, adding that its mission was to become the "most trusted Chinese online news service by insisting on 'Independence' and 'Journalistic Objectivity.'"

"Boxun News has apparently abandoned this mission in its quest for salacious headlines at the expense of Ms Zhang," said the lawsuit.