A Syrian witness who has accused al-Hariri's son Saad of bribing him to testify falsely, said on Monday that a report by UN investigator Detlev Mehlis implicating Syrian and Lebanese officials in the assassination was based mainly on his own lies.
Jumblatt said the allegations of Hussam Tahir Hussam, a former Syrian intelligence agent, were part of a Syrian campaign to discredit Mehlis before UN investigators question five Syrian witnesses in Vienna.
"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 said on Tuesday.
The Druze leader, an erstwhile ally of Damascus who turned into a fierce critic of Syria's military presence in Lebanon, said the Syrians still had a security network in the country.
Syria dominated its neighbour politically and militarily for almost three decades until a Lebanese and international outcry over al-Hariri's death forced it to withdraw its troops in April.
Hussam Tahir Hussam (L) is a
former Syrian intelligence agent
A series of bombings and assassinations has rocked Lebanon since, targeting politicians and prominent journalists.
In a televised news conference in Damascus, Hussam 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 UN investigation has confirmed Hussam was a witness but said he signed a statement on 1 September 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 the Mehlis report.
"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"
Lebanese Druze leader
Hussam's appearance came after Damascus agreed to allow five Syrian officials to be questioned at UN offices in Vienna in connection with the Beirut truck bombing that killed al-Hariri.
"We will not rest until we see the suspects behind bars," Jumblatt said of those behind the 14 February assassination.
"What does the timing of this person's (Hussam'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."