MUKHTARA, Lebanon, Nov 29 (Reuters) – Lebanese Druze leader Walid Jumblatt accused Syria on Tuesday of trying to destabilise Lebanon to undermine a U.N. inquiry implicating Damascus in the killing of former Prime Minister Rafik al-Hariri. A Syrian witness who has accused Hariri’s son Saad of bribing him to testify falsely said on Monday a report by U.N. investigator Detlev Mehlis implicating Syrian and Lebanese officials in the assassination was based mainly on his own lies.

Jumblatt said the allegations of Hosam Taher Hosam, a former Syrian intelligence agent, were part of a Syrian campaign to discredit Mehlis just before U.N. investigators question five Syrian witnesses flown to Vienna to meet them."This political senility and this deception by the Syrian security apparatus is a laughable farce and at the same time it seems they will use all means, even security, to shake up security (in Lebanon) to try to confuse the inquiry," Jumblatt told Reuters television

The Druze leader, an erstwhile ally of Damascus who turned into a fierce critic of Syria’s military presence in Lebanon, said the Syrian still had security networks in the country.Syria dominated its neighbour politically and militarily for almost three decades until a Lebanese and international outcry over Hariri’s death forced it to withdraw its troops in April.

 series of bombings and assassinations has rocked the country since, targeting politicians and prominent journalists.

In a televised news conference in Damascus, Hosam also accused Jumblatt and Lebanese Telecommunications Minister Marwan Hamadeh of getting other witnesses to testify falsely to Mehlis.

Jumblatt and Hamadeh have denied the allegations.

The U.N. investigation has confirmed Hosam was a witness but said he signed a statement on Sept. 1 saying that he was testifying voluntarily and had not been forced, threatened or given incentives. It made no comments on his assertions about the weight placed on his testimony in Mehlis’s report.

Hosam’s appearance came after Damascus agreed to allow five Syrian officials to be questioned at U.N. offices in Vienna in connection with the Beirut truck bombing that killed Hariri.

"We will not rest until we see the suspects behind bars," Jumblatt said of those behind Hariri’s Feb. 14 assassination.

"What does the timing of this person’s (Hosam’s) appearance mean?" Jumblatt asked. "On the verge of the Vienna meeting, they are trying, and will not succeed, to shake Mehlis’s credibility. We trust Mehlis and the international investigation."