Iraqi insurgents attacked U.S.-led coalition forces Saturday, amid new calls for a cease-fire to end a week of fighting that has killed hundreds of people in Iraq.

American troops and insurgents in Aadhamiya, a Sunni Muslim district of northwest Baghdad traded heavy gunfire, and fighting also was reported in Baqouba, north of the capital, and in Fallujah, west of Baghdad, the scene of this week's most prolonged and intensive fighting.

In an attack reminiscent of Friday's assault on a fuel convoy at Abu Ghreib, witnesses say guerrillas firing rocket-propelled grandes hit a tanker and a truck near Baghdad airport, setting the vehicles ablaze.

In northern Iraq, officials of the Iraqi Red Crescent Society say the aid group's director in the Kurdish city of Arbil and his wife have been murdered. The victims were found shot to death Friday in the city of Mosul.

Saturday's violence showed little sign of easing despite a call by the U.S.-led coalition for insurgents in Fallujah to join a cease-fire, beginning at midday.

Iraq's interim Governing Council added its voice to those calling for a cease-fire between U.S. forces and Muslim militants, in the hope this will help the search for a political solution to Iraq's many problems.

In Karbala, in central Iraq, leaders of a militia loyal to radical Shi'ite cleric Moqtada Sadr say they, too, will observe a cease-fire in the holy city to allow pilgrims to observe the al-Arba'een religious holiday.

Hundreds of thousands of pilgrims, many of them from Iran, are in Karbala and other Shi'ite cities, taking part in the annual mourning period for a seventh-century Shi'ite martyr.

Italian Prime Minister Silvio Berlusconi traveled to Iraq today to visit with Italian troops in the southern city of Nasiriyah. Officials of the Rome government say the spreading rebellion in Iraq will have no effect on plans for the 2900 Italian troops in Iraq to be withdrawn despite the widening insurgency.