The U.N. Security Council has authorized an international investigation into the assassination of former Lebanese Prime Minister Rafik Hariri.  Investigators will have broad powers in conducting their probe.

A resolution authorizing an international investigation passed unanimously, after language was added ensuring respect for Lebanon's sovereignty.

Council diplomats hailed the measure as a firm step toward determining who was responsible for the bomb that killed the former Lebanese prime minister. Deputy U.S. Ambassador Stuart Holliday noted that Lebanese authorities had sent a letter to the Council pledging full cooperation with the international probe.

"It's important to recognize that the government of Lebanon has indicated that they will cooperate. We expect them to hold to their word, and that includes all aspects of the government of Lebanon," Mr. Holliday said.

France joined with the United States as main sponsors of the resolution. French Ambassador Jean-Marc de La Sabliere said he was satisfied that language in the measure avoids any intrusion by the international investigation on Lebanon's sovereignty.

"It is important that the conclusions of this commission are carried out by the legal system in Lebanon, and it is important that this commission acts independently, but also in the framework of Lebanese sovereignty. And there will be no contradiction, because the Lebanese authorities will totally cooperate," Ambassador de La Sabliere said.

The measure calls on the secretary-general to appoint a commission that would have broad investigative powers. The panel would have three months to complete its probe, though the mandate could be extended to six months, if necessary.

Mr. Hariri died in a mysterious explosion February 14 near his home in Beirut. The assassination touched off massive street demonstrations, as well as increased international pressure on Syria to withdraw from Lebanon. A full Syrian withdrawal has been promised by April 30.

Lebanese opposition leaders accused Syria of orchestrating the killing, a charge Damascus vehemently denies.

Demands for an international investigation were raised after a U.N. fact-finding mission concluded that a Lebanese probe suffered from serious flaws, which prevented it from reaching a credible conclusion.