In the interview broadcast Friday on al-Arabia television, Abdel-Halim Khaddam, who had headed much of Syrian political and military strategy in Lebanon before he resigned last summer, said Assad confronted Hariri during an August 2004 meeting in Damascus.
According to Khaddam, the Syrian president warned Hariri "in extremely harsh words," not to interfere with Assad's plan to extend the term of his Lebanese ally, President Emile Lahoud. Khaddam quoted the Syrian president as telling Hariri in 2004: "You want to bring a [new] president in Lebanon. I will not allow that. I will crush whoever attempts to overturn our decision."
Hariri continued to resist efforts to extend Lahoud's term and opposed other Syrian interests in Lebanon until he was killed in a massive truck bombing on Feb. 14, 2005 in Beirut.
A preliminary report by a United Nations panel investigating the bombing that killed Hariri and 20 others concluded that the attack was a terrorist act carried out by high-ranking Syrian and Lebanese intelligence officers.
Khaddam, who is writing a book while in exile in Paris, said any involvement by Syrian intelligence officials would need to be sanctioned by people in power in Damascus.
"We must await the results of the investigation, but no Syrian security service could take such a decision unilaterally," Khaddam said.
Syria has denied any involvement in the killings, but according to Reuters, a U.N. official said that Khaddam's statement "corroborates information the commission has received."
Officials with the U.N. inquiry said Monday they were seeking interviews with Assad and the country's foreign minister who earlier described the meeting between the Syrian president and Hariri as cordial. Nasra Hassan, who speaks for a U.N. commission heading the probe, also said investigators want to interview Khaddam "as soon as possible."
"The U.N. commission has already sent a request to interview Syrian President Bashar Assad and Foreign Minister Farouk al-Sharaa, among others," Hassan told the Associated Press.
"The commission is waiting for a response from the Syrians," she said. She refused to say when the request was made.
U.S. Ambassador to the United Nations John Bolton, who has called on Syria to cooperate with the Hariri inquiry, urged Damascus to grant the request.
"We strongly support the commission's investigative efforts," Bolton said in a statement Monday. "We expect the government of Syria to comply with these requests fully and unconditionally as the Security Council resolutions require."
In Syria, Khaddam's comments have sparked a firestorm of condemnation and prompted the Syrian government to seek the former vice president's trial on charges of treason.
On Saturday, Syria's parliament voted to request a trial on treason charges. The next day, the ruling Baath party stripped Khaddam of his membership in a fiery statement that condemned the long-time ally of former Syrian president Hafez Assad.
"Khaddam has joined the band of enemies who are targeting the country and its attitudes," the Baath Party said in a statement. "Khaddam has betrayed the party, the country and the (Arab) nation. The National Leadership has decided to dismiss Khaddam from the party and put him on trial."
Although Khaddam has expressed hope he could return to Syrian one day, the Syrian government made its threat to put him on trial official on Monday.
"The Council of Ministers will take the necessary measures to try Khaddam for high treason, and to open an inquiry into corruption in a series of matters which will include seizing his assets," the official daily newspaper Ath-Thawra said Monday.
Syria's ruling Baath party said Sunday it had expelled the ex-vice president for comments it described as "slander which violates the principles of the nation".
If found guilty of the charges, Khaddam could be put to death.