(Bloomberg) -- President George W. Bush said the U.S. won't let Syria and Iran undermine Lebanon's sovereignty, as clashes erupted in the northern city of Tripoli between gunmen allied to Hezbollah and supporters of the government.

"It is critical that the international community come together to assist the Lebanese people in their hour of need," Bush said in a statement late yesterday, adding he plans to discuss the issue with regional leaders during his Middle East trip this week.

Hezbollah, which the U.S. regards as a terrorist group, withdrew its fighters from western neighborhoods of Beirut two days ago after the government backed down on a threat to disrupt its covert phone network and electronic surveillance system at Beirut's international airport.

While the capital remained calm yesterday, fighting broke out in Tripoli between Sunni Muslim gunmen loyal to Prime Minister Fouad Siniora's government and members of the Alawite sect of Islam, who are aligned with a pro-Syrian party and the Hezbollah-led opposition.

The U.S. will continue to assist the Lebanese Armed Forces so they can defend the government, Bush said. "The international community will not allow the Iranian and Syrian regimes, via their proxies, to return Lebanon to foreign domination and control."

Airport Security

Violence in Lebanon broke out May 7 after the government fired the head of airport security, following the discovery of Hezbollah's surveillance system.

Hezbollah leader Hassan Nasrallah, whose group fought a 33- day war against Israel in 2006, said the system is needed to protect Lebanon from Israeli invasion.

Hezbollah has been trying to oust the Siniora government since November 2006, when the Shiite group's lawmakers and allies walked out of the cabinet demanding veto powers.

Siniora's ruling coalition includes Sunnis, Christians and Druze and is backed by the U.S., Saudi Arabia, Egypt and other American allies in the Middle East. The Hezbollah-led opposition counts on support from a Christian party and a small Druze grouping and is backed by Syria and Iran.

A scheduled vote by lawmakers to elect a new president today will probably be postponed a 19th time, said Ali Hamdan, spokesman for Parliament Speaker Nabih Berri.

Arab League

Arab League Secretary General Amr Moussa plans to head a delegation to Lebanon that will try to resolve the crisis. The 22-member Arab League is expected to press all parties in Lebanon to return to talks and to order their supporters to stop the violence immediately.

Fighting was also reported yesterday along Lebanon's eastern border with Syria, said Army Brigadier Saleh Haj Suleiman. A cease-fire was holding between Hezbollah fighters and Druze backers of Walid Jumblatt, who is aligned with Siniora, in the towns of Aley and Shweifat, Suleiman said.

The death toll from last week's fighting may have reached more than 80 people, Suleiman said. Not all the casualties have been accounted for, he said.

The International Red Cross has registered 39 dead and 75 wounded, spokesman Ayad Mounzer said yesterday.

The Bush administration accuses Syria of trying to undermine democracy in Lebanon and has implicated it in the 2005 car bombing that killed former Lebanese Prime Minister Rafiq Hariri. Public outrage over the assassination prompted Syrian President Bashar al-Assad to comply with international demands and withdraw his troops from Lebanon after a 29-year occupation.

Syria has denied any involvement in Hariri's death and other political killings in Lebanon.

By Massoud A. Derhally