President Bashar Assad indicated Saturday he was rejecting a second request by U.N. investigators to interview him about the assassination of Lebanon's former prime minister, declaring that Syria would not bow to international pressure.

Assad's uncompromising tone against the United Nations on what he termed a matter of national sovereignty was certain to further heighten tension with the United States and complicate the seven-month probe into the Feb. 14 truck bombing that killed Rafik Hariri and 20 others on a Beirut street.

"We should not give up our national sovereignty even if the circumstance requires that we fight for our country. We must be prepared for that," he said.

The U.N commission investigating Hariri's assassination has implicated top Lebanese and Syrian security officials. Syria rejected the findings and tried to discredit commission witnesses.

In his speech to the Arab Lawyers Union, however, Assad pledged to continue cooperation with the probe. The U.N. investigation has said Syria has not been sufficiently forthcoming and the Security Council demanded full cooperation.

"We will continue to cooperate with the investigation currently and in the future in order to find the truth," he said.

The Syrian leader did not specifically address the request by the U.N. investigation to interview with him and his foreign minister about threats Assad allegedly made against Hariri months before the Feb. 14 assassination.

That left open the possibility that Assad might later agree to meet with U.N. investigators, rather than submit to an interview.

In press interviews after his recent defection to France, former Vice President Abdul-Halim Khaddam said Assad had either known about or gave the orders for the assassination.

Assad has denied threatening Hariri. He made no reference to Khaddam in his wide-ranging speech.

Assad rejected a request by the investigation to interview him last year as well. But the arrival of the new chief investigator, Serge Brammertz, in Beirut on Thursday could provide a fresh start.

In the speech Saturday, Assad repeatedly was interrupted by applause and shouts of support.

"(Even) if all the Arab, Islamic and world rulers agree that Bashar Assad be questioned, we will prevent you by force (from submitting)," said Arab Lawyers Union head Sameh Ashour of Egypt.

In November, Assad criticized the investigation as politicized by the United States and its allies with the aim of framing Syria to punish it for its opposition to the Iraq war, support for Palestinian militants and Lebanese guerrillas.

The U.N. Security Council has twice found that Syria has failed to cooperate fully. There were U.S. warnings that the council might take further action, and American officials have called on Syria to change its policies on the investigation, Lebanon, Iraq and the Palestinian issue.

The assassination led to international pressure that forced Syria to withdraw its army from Lebanon in April, ending nearly three decades of political and military control of the neighboring country.

The investigation has split the Lebanese people and heightened tension between Syria and the United States.

Assad also used his speech to accuse Israel of killing Yasser Arafat in 2004, capitalizing on the widespread belief in the Arab world that the Palestinian leader was poisoned.

"This was under the world's eyes and its silence, and not a single state dared to issue a statement or stance toward this issue, as if nothing has happened in this region," Assad said.

Arafat died in 2004 in a French hospital. French medical records obtained by The Associated Press said he died of a stroke caused by a mysterious infection. Rumors persist that Arafat died of AIDS or was poisoned by Israel, a charge Israel has denied.

In a further sign that his position is hardening, Assad consolidated his alliance with Iran, another country facing international pressure and the threat of sanctions over its nuclear program, holding a summit with Iranian President Mahmoud Ahmedinejad in Damascus this week.