More soldiers fanned out through Beirut, with orders to use force to restore security to a nation shaken by nearly a week of sectarian clashes. Lebanese buried more of their dead and tried to resume life in a capital dissected by roadblocks.

What began as a political struggle 11/2 years ago with Shiite ministers bolting from the cabinet devolved last week into Lebanon's worst fighting since the end of the 1975-90 civil war, with at least 54 people dead and scores wounded.

Shiite Hezbollah guerrillas and allied Amal gunmen have swept through large Sunni swaths of Beirut, in neighborhoods that support the government of Prime Minister Fuad Saniora, a Sunni.

Yesterday, the strife between Lebanon's government supporters and opponents expanded into a wider regional standoff between Sunni powerhouse Saudi Arabia and the world's largest Shiite nation, Iran. Iran supports Hezbollah and Saudi Arabia backs Saniora's Sunni-led government.

"Of course, Iran is backing what happened in Lebanon, a coup, and supports it," Saudi Foreign Minister Saud al-Faisal told a news conference in Riyadh, in the most pointed criticism of Tehran. "This will affect [Iran's] relations with all Arab countries, if not Islamic states as well."

Iranian President Mahmoud Ahmadinejad shot back by saying Saud's comments were made in anger and likely did not conform to the views of Saudi King Abdullah. He said Iran was the only country that does not interfere in Lebanon's internal affairs.

President Bush weighed in Monday, telling Al-Arabiya television that Washington would continue to support the Lebanese government and military, and would keep up pressure on Iran and Syria. The United States considers Hezbollah a terrorist organization and has repeatedly called for it to disarm.

As Bush arrives in the Middle East today for a trip that includes visits to Saudi Arabia and Egypt - as well as peace efforts between Israel and the Palestinians - the flare-up is a sign that nervousness is growing about Iran's expanding influence.

Sunni Arab countries such as Saudi Arabia and Egypt worry that Iran wants to flex its muscle and assume a larger and strategic role in the region - taking power and influence that was historically theirs. Iran, in turn, accuses U.S.-allied Arab countries such as Egypt of merely bending to America's will and pushing its agenda in the region.

The growing tension has wide implications for American and Western goals in the region, with the West generally allied more with the Arab governments and also worried about Iran's intentions.

The same dynamic is playing out over Iraq, which also has been a strong source of discord among Arab countries, who generally support Sunnis there, and Iran, which is closely allied to both the Shiite-led government and to Shiite splinter groups like the Mahdi Army.

An Arab League delegation was expected in Beirut this week to try to bring Lebanon's feuding parties toward consensus, and resolve a troubling political crisis that has left the country without a president since November.

Violence erupted last week after the U.S.-backed government sacked the airport security chief for alleged ties to Hezbollah, and declared the extremist group's private telephone network illegal.

Hezbollah revolted and drove out the government's Sunni supporters in street fighting that spread from the capital to mountains overlooking Beirut and even to the northern city of Tripoli. A cease-fire largely halted the clashes Monday.