BAGHDAD (AP) -- U.S. marine jets attacked two bridges across the Euphrates River near the Syrian border on Tuesday to prevent insurgents from moving foreign fighters and munitions toward Baghdad and other cities, the U.S. command said.

A marine statement also said U.S. and Iraqi forces destroyed a "foreign fighter safe house," killed two foreigners and arrested three others during a Tuesday raid in the same area as the bridge attack.

Elsewhere, Iraqi civilians said they could see smoke rising from the northern city of Tal Afar, where fighting has been raging for days between U.S.-Iraqi forces and insurgents said to include foreign fighters.

The U.S. command said one American soldier was killed Monday in Tal Afar and two were killed and two wounded Tuesday by a roadside bomb. At least 1,892 members of the U.S. military have died since the war began in March 2003, according to an Associated Press count.

Witnesses saw ambulances evacuating at least 10 injured civilians from the city Tuesday.

The fighting occurred after UN chief Kofi Annan said Iraq had become an even greater terrorist centre than Afghanistan under the Taliban. Attacks attributed to al-Qaida's wing in Iraq have stepped up in the Baghdad area and western Iraq.

A marine statement said F/A-18 jets dropped bombs shortly after midnight on two light bridges near Karabilah, about 300 kilometres west of Baghdad.

"The purpose of the strike was to prevent 'al-Qaida in Iraq' terrorists from using the structures for vehicular traffic to conduct attacks," the U.S. statement said. "The munitions used in the strike were designed to crater the bridges, rendering them inoperable but not destroying them."

The clash at the safe house occurred when U.S. and Iraqi troops came under fire by foreign fighters occupying the building, the marines said.

"Multinational forces personnel returned fire and assaulted the building, suffering one friendly casualty when a Multinational Force soldier was wounded," the statement said without citing the soldier's nationality.

Troops called in aircraft to destroy the building, which was being used as an operational headquarters, the statement added.

Karabilah is one of a cluster of towns near the Syrian border, a major infiltration route for foreign fighters heading for Baghdad and other major cities. Iraqi officials say "al-Qaida in Iraq," led by Abu Musab al-Zarqawi, has taken over parts of the area after residents fled fighting between tribes supporting and opposing the insurgents.

Meanwhile, the U.S. army handed over its base in Najaf on Tuesday, giving Iraqis full control of the city as a first step in transferring security across the country so multinational forces can begin to return home.

Lt.-Col. James Oliver, the U.S. commander of Forward Operating Base Hotel, handed the ceremonial keys to the installation to the new Iraqi commander, Col. Saadi Salih al-Maliky. About 1,500 Iraqi soldiers from the 2nd Battalion, 1st Brigade, 8th Division marched by.

U.S. forces have relocated to another base farther outside the city so they would be available to assist in a major security crisis.

Najaf, about 160 kilometres south of Baghdad, is the holiest city in Iraq for Shiite Muslims and was the scene of heavy fighting last year between the U.S. army and the militia of radical Shiite cleric Muqtada al-Sadr.

In statements posted on Islamic websites, "al-Qaida in Iraq" claimed responsibility for two attacks Monday - a roadside bombing that killed two British soldiers west of Basra and a daylight assault against the Interior Ministry in Baghdad in which two policemen died.

Elsewhere, Iraqi officials said al-Qaida-linked foreign fighters had taken control of large areas of a strategic city on the Syrian border after weeks of fighting between an Iraqi tribe that supports the insurgents and one that opposes them.

The officials, speaking on condition of anonymity for fear of reprisal, said much of Qaim, 320 km west of Baghdad, had been abandoned.

U.S. marines operate around Qaim but have complained privately that they do not have enough American or Iraqi forces to secure the area properly.

On Monday, gunmen seized a son of the governor of insurgent-infested Anbar province, Mamoun Sami Rashid al-Alwani, officials said. The abduction occurred in the provincial capital of Ramadi, west of Baghdad.

U.S. and Iraqi officials had hoped the new constitution, which goes to the voters in an Oct. 15 referendum, would help pacify the insurgency by luring Sunni Arabs away from it.

However, Sunni negotiators rejected the constitution and vowed to defeat it in the referendum. The bitter, protracted negotiations appeared to have raised tensions among Iraq's ethnic and religious communities.

Officials said last week they were considering some minor changes in the constitution to appease the Sunnis. But Shiite legislator Ali al-Dabagh said Tuesday the only change would be to add language affirming Iraq's status as a founding member of the Arab League to allay fears of Iraq's Arab neighbours.

The language at issue describes Iraq as an Islamic - but not Arab - country, a concession to the non-Arab Kurds who form about 15 per cent of the Iraqi population.

On Monday, President Jalal Talabani said he and the other top Kurdish leader, Massood Barzani, had agreed to adding references to the Arab League.

By Sameer N. Yacoub