(Adds Odierno, paragraphs 6-8) By Alister Bull BAQUBA, Iraq, June 22 (Reuters) - Thousands of U.S. soldiers on the offensive north of Baghdad are facing fierce resistance from hundreds of al Qaeda militants who are ready to fight to the death, an American general said on Friday. The militants are making their stand in and around the Iraqi city of Baquba, 65 km (40 miles) north of Baghdad, where the U.S. military on Tuesday launched one of its biggest operations since the invasion of Iraq in 2003. "It is house to house, block to block, street to street, sewer to sewer," said Brigadier-General Mick Bednarek, commander of Operation Arrowhead Ripper in Iraq's Diyala province. Not far from Baquba, U.S. attack helicopters killed 17 suspected al Qaeda gunmen on the outskirts of the town of Khalis early on Friday, the U.S. military said. The military said those killed were armed and had been acting suspiciously around an Iraqi police patrol. That brings to 68 the number of militants killed so far in the operation. A top U.S. commander suggested it could be spring before Iraqi forces were ready to take responsibility for areas cleared by U.S. troops in Arrowhead Ripper and other operations taking place around Baghdad as part of a broader offensive. "I think if everything goes the way it's going now, there's a potential that by the spring we would be able to reduce forces and Iraqi security forces could take over," Army Lt. Gen. Ray Odierno said. Odierno, the top commander for day-to-day operations in Iraq, told Pentagon reporters by videolink that Iraqi forces might be ready sooner but it was hard to predict exactly when. U.S. officials accuse Sunni Islamist al Qaeda of using car bombings and other violence to try to tip Iraq into full-scale sectarian civil war. A suicide truck bomb blamed on al Qaeda killed 87 people outside a Shi'ite mosque in Baghdad on Tuesday. Bednarek estimated several hundred al Qaeda militants were at Baquba and it would be a long and dangerous job for U.S. forces to flush them out. "They will not go any further. They will fight to the death," Bednarek told Reuters and another news agency. "There have been houses that were used by al Qaeda as safe houses ... their entire structures rigged with massive explosives." Baquba is the capital of Diyala province. The region has long been an al Qaeda hotbed, but attacks against U.S. and Iraqi forces have soared here since a four-month-old U.S.-led security crackdown in Baghdad and operations elsewhere prompted many al Qaeda militants and other gunmen to seek sanctuary in Diyala. The campaign is part of a broader offensive involving tens of thousands of U.S. and Iraqi soldiers pushing on with simultaneous operations in Baghdad, and to the south and west of the capital. Tough fighting is expected over the next 45-60 days, U.S. military officials have said, sketching a rough timeline for the combined operations. TORTURE HOUSE Bednarek said U.S. forces were making some grisly discoveries as they scoured Baquba. He said residents led soldiers to a house in the western part of the city that appeared to have been used to hold, torment and kill hostages. Soldiers destroyed it. "When you walk into a room and you see blood trails, you see saws, you see drills, knives, in addition to weapons, that is not normal," Bednarek said. U.S. military commanders have said the combined operations were taking advantage of the completion of a build-up of American forces in Iraq to 156,000 soldiers. President George W. Bush has sent 28,000 extra troops mainly to Baghdad to help curb sectarian bloodshed and buy time for Shi'ite Prime Minister Nuri al-Maliki to reach a political accommodation with disaffected minority Sunni Arabs, who are locked in a cycle of violence with majority Shi'ite Muslims. U.S. casualties have been light so far, given the scope of the offensive in Diyala, with one soldier killed, although in Baghdad roadside bombs are exacting a heavy toll. Bednarek said the fight against al Qaeda in Diyala also involved local Sunni Arabs who opposed the United States but who wanted to end al Qaeda domination of their communities. He said this included fighters from the 1920 Revolution Brigade, a large Sunni Arab insurgent group that has fallen out with al Qaeda over its indiscriminate killing of civilians. (Additional reporting by Paul Tait in Baghdad and Andrew Gray in Washington)
