US warplanes and helicopter gunships firing heavy machine-guns, rockets and cannons hammered gunmen as a truce in besieged Fallujah was strained by increasingly intensive gunbattles. With more troops killed, April became the deadliest month for American forces since they set foot in Iraq.

　　Elsewhere, a 2,500-strong US force massed on the outskirts of the Shiite holy Najaf for a showdown with a radical cleric, raising fears of a US attack on the city that would outrage the nation's relatively pro-US Shiite majority.

　　Russia announced that it will evacuate its citizens from Iraq following a spate of kidnappings of at least 22 foreigners that erupted with the violence this month.

　　US troops were holding back their full firepower on both fronts to allow Iraqis to try to negotiate a resolution, but President George W. Bush said he was prepared to send more troops and had told his commanders to be ready to use "decisive force."

　　"Our work may become more difficult before it is finished," Bush said. "No one can predict all the hazards that lie ahead or the cost that they will bring. Yet, in this conflict, there is no safe alternative to resolute action."

　　With the announcement of the deaths of four more Marines, April became the deadliest month for the US military in Iraq - deadlier even than the invasion launched in March 2003. At least 87 troops have been reported killed in action in less than two weeks. Previously, November had seen the most deaths, 82.

　　Some 880 Iraqis have been killed this month. Among those are more than 600 Iraqis - mostly civilians - killed in Fallujah, according to the city hospital's director.

　　A US Cobra attack helicopter fired rockets and heavy machine-guns before dawn yesterday at gunmen gathered on the northern edge of the city of Fallujah. Rocket-propelled grenades arched up from the ground toward the helicopter and a second gunship providing support, but none apparently hit the gunships.

　　Early yesterday, A-130 gunships pounded a row of buildings from which Marines say ambushes have repeatedly been launched in a residential area of the city.

　　A day earlier, Marines came under two heavy ambushes, the best coordinated and largest guerrilla operations in days, said Captain James Edge. Two Marines were killed on Tuesday and two on Monday, the military announced.

　　"I think they are absolutely taking advantage" of the truce, said Lt. Colonel Brennan Byrne deployed on the southern side of the city.

　　A force of 20 insurgents attacked a Marine position in a residential neighborhood, then damaged an armored vehicle that came to support it, Edge said.

　　A fierce battle followed to extract the vehicle as F-15s overhead fired on gunmen. Early yesterday, A-130 gunships fired on a row of buildings in the area from which ambushes have repeatedly been launched, Edge said.

　　Outside the city, an MH-53 Pave Low helicopter - used to ferry special operations soldiers and large enough to carry 38 troops plus a crew of six - was hit by ground fire early on Tuesday. A Marine team that came to secure it was ambushed and suffered casualties.

　　The Marines called a halt to offensive operations on Friday to allow negotiations between US-allied Iraqis and Fallujah representatives in an attempt to ease the violence. Gunmen in the city called a cease-fire on Sunday. But Marines have been responding to guerrilla fire - and striking gunmen who appear about to attack.

　　Insurgents yesterday offered the Iraqi equivalent of US$7,000 for anyone who kills Mouwafak al-Rubaie, the Iraqi national security adviser, after he called for Fallujah's residents to handover militants to the United States.

　　"We announce a bounty of 10 million Iraqi dinar for whoever brings the head of this pig," the statement said.

　　The US State Department on Tuesday confirmed that four bodies have been found in Iraq, possibly the remains of private contractors missing since an assault on their convoy outside Baghdad.

　　An AP tally shows that 22 hostages are being held, including three Japanese whose captors have threatened to kill them. At least 35 others had been taken hostage and released. Nine Americans, including two soldiers, were missing.

　　Russia will begin evacuating some 800 of its citizens and citizens from the Commonwealth of Independent States from Iraq today, the Emergency Situations Ministry announced yesterday. France is also urging its citizens to leave the country.

　　The move comes after three Russian and five Ukrainian employees of a Russian energy company were kidnapped by masked gunmen who broke into their Baghdad house on Monday.

　　(The Associated Press)