Sen. Patrick Leahy, a Vermont Democrat, made the comments to reporters after meeting U.N. Secretary-General Kofi Annan on a variety of issues and offering him support.

``I have seen enough of the evidence on Hariri to know that they (Syrians) were behind it,'' Leahy said without elaborating. ``I don't think there is a single person in Lebanon and probably no one in Syria who doesn't believe they were behind it.''

``There is no question -- no question in my mind -- that they were behind the assassination,'' the senator said.

Syria has denied involvement in the killing.

The United Nations has sent a team to Lebanon to investigate the February assassination, which gave rise to mass anti-Syria protests.

Syria in May withdrew its forces from Lebanon, which had been in that country for nearly three decades, but Leahy, a member of the Senate Appropriations Committee, said no one could say for certain Damascus had removed all its intelligence personnel.

Annan on Monday asked Terje Roed-Larsen, a special envoy, to return to Damascus for ``full implementation'' of a Security Council resolution demanding the withdrawal of Syrian military and intelligence personnel from Lebanon and the disarming of guerrilla groups.

But U.N. spokesman Stephane Dujarric could not say what Roed-Larsen was doing in Syria except to say the council's resolution had ``many facets'' that needed to be implemented.

The United States also wants the U.N. Security Council to investigate the car bombing death of a prominent anti-Syrian Lebanese journalist last Thursday. But no action has been taken yet on the death of Samir Qaseer, who wrote for the An-Nahar newspaper and was killed in a blast outside his Beirut home.

Leahy said he agreed with the Bush administration on pursuing the journalist's death but that he had seen no evidence on the perpetrators. (Reuters)