BEIRUT, Lebanon - Syria is fighting back hard against the U.N. inquiry into the slaying of a Lebanese politician, touting a witness who says his testimony against Syrian officials was false.

Some say Bashar Assad's government is just trying to discredit an investigation that could lead to its doorstep.

Syrian barber and self-proclaimed intelligence operative Husam Taher Husam came forward Sunday with claims he lied to investigators about Syria's involvement in the Feb. 14 bombing in Beirut that killed Rafik Hariri, a former Lebanese prime minister.

Husam alleged he had been offered money by the Hariri family and Lebanese officials to frame Syria, accusations rejected in Beirut.

Syria and its allies in Lebanon say Husam's claims are a blow to the inquiry's credibility, and the Syrian government has put him on state television three times in four days to tell his story.

But Syria's Lebanese opponents suspect Damascus planted Husam to undermine the U.N. commission and its lead investigator, German prosecutor Detlev Mehlis.

Walid Jumblatt, a leader of the campaign to drive Syria from Lebanon, ridiculed the TV appearances as a ``laughable farce'' carried out by Syrian intelligence. He said the appearances were aimed at undermining Mehlis' credibility before he questions five senior Syrian officials implicated in the probe.

The timing of the questioning in Vienna has not been announced, although the Syrians are not expected to arrive there until next week, the Austrian Interior Ministry said.

Mehlis's interim report to the U.N. last month said Syria - which controlled Lebanon at the time of Hariri's assassination - must have known about, and may have been involved in, the plot to kill him.

Syria denies any role in Hariri's death and its officials have rejected the interim report, accusing Hariri's son, Saad, and his political allies in Lebanon of seeking to frame Syria with the backing of the United States.

A Syrian judicial committee conducting its own inquiry said Husam's revelations dealt a ``knockout blow'' to the Mehlis report.

Mehlis has confirmed that Husam was a witness in his probe but has not commented on the impact of his recantment.

Chibli Mallat, a professor of international law who is campaigning to be Lebanon's next president, called Husam's appearance a ``childish spoof'' and said he didn't believe it would have much practical effect on Mehlis' inquiry.

``My sense is that they (investigators) didn't take his inital testimony seriously,'' he told The Associated Press.

The commission - which began work in June and could extend it beyond a Dec. 15 deadline - has faced other problems.

A man who was questioned about the sale of cellular phone chips used by those allegedly involved in Hariri's bombing was found dead last week on a mountain road northeast of Beirut, in what was ruled as a car accident.

One of four pro-Syrian security generals charged with involvement in the killing, former military intelligence chief Raymond Azar, was rushed from jail to a hospital with heart problems on Wednesday. He was reported in stable condition in the intensive care unit.

Ghazi Kenaan, the Syrian interior minister who ran Lebanon for two decades, died in his office in Damascus about a month after being interviewed by the commission. Syrian officials declared it a suicide but some in Lebanon believe he was killed.  (AP)