The Syrian Government said that Ghazi Kanaan, 63, the Interior Minister and former head of Syrian military intelligence in Lebanon, had committed suicide in his office in central Damascus. “The relevant agencies are investigating,” a statement published by the SANA national news agency said.

Last night Bashar al-Assad, the Syrian President, denied that his regime was involved in the assassination and said that any official found guilty would be tried for treason. “If they are implicated, they should be punished.” the President said. “This is against our principle and my principle. I would never do such a thing in my life.”

In spite of his denials, many in Lebanon regard the latest twist in the plot as evidence that the Syrians are involved.

Marwan Hamade, the Lebanese Minister of Telecommunications who survived an assassination attempt a year ago, said: “It’s certainly related to the Hariri inquiry and absolutely will have an impact because a major witness has disappeared.”

Other prominent Lebanese were also sceptical that General Kanaan committed suicide. Jibran Tueni, the general manager of Lebanon’s an-Nahar newspaper, said: “I don’t believe in the suicide story. The regime is worried that he knew too much about Syria’s behaviour inside and outside Lebanon. What happened today is proof that the Syrian regime is feeling the (UN) report is getting closer to them, and they are beginning to panic.”

Mahdi Dakhlallah, the Syrian Information Minister, told al-Arabiya television that the death would not affect political stability in Syria, adding that General Kanaan had appeared to be “very upset and angry” over the anti-Syrian campaign waged in Lebanon.

General Kanaan was a powerful figure from the Alawite community, an offshoot of the Shia branch of Islam that forms the backbone of the Baathist regime in Syria. Some analysts believe that he was a potential candidate to replace the youthful President Assad, and that he may have had the tacit backing of some American officials.

“Washington has been talking about the adults taking over from the children, and Kanaan was one of the last of the so-called ‘old guard’. He was considered a real force,” Joshua Landis, a professor of history based in Damascus, said. “It’s hard to believe Kanaan would commit suicide. He was an active, hard-working man who overcame many hard times in his life.”

Detlev Mehlis, a German prosecutor, and his 100-strong team of investigators and technicians have spent four months doggedly tracking Mr Hariri’s killers, interviewing hundreds of people including, three weeks ago, General Kanaan and other key Syrian officials involved with Lebanon. The findings of the investigation are to be submitted to the UN Security Council next week.

Damascus, already under intense pressure from the US over Iraq, insists that it had nothing to do with the February 14 bombing in central Beirut that killed Mr Hariri and 19 others.

The Lebanese media has been agog with speculation over the results of the report. On Tuesday night, the New TV channel broadcast allegations that General Kanaan had admitted to Mr Mehlis that he had amassed millions of dollars during his “reign in Lebanon”.

“Premier Hariri had at the time given me a $10 million cheque,” New TV quoted General Kanaan as saying in his testimony to the UN investigators. “We were making money from Premier Hariri so how could we possibly kill him and close the flow of his riches?” Yesterday morning General Kanaan spoke to the Voice of Lebanon radio station to reject the allegations aired the previous evening.

“My testimony (to the UN investigators) was to shed light on an era during which we served Lebanon,” he said. “I want to make clear that our relation with our Lebanese brothers in Lebanon was based on love and mutual respect.”

He ended his comment: “I think this is the last statement I might give.” His body was found three hours later.

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