Damascus, Syria ? 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.

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.