US troops have come under mortar fire in Saddam Hussein's home town of Tikrit, a focal point of post-war resistance in Iraq. No US casualties were reported in the ferocious fire fight that followed but at least one Iraqi is thought to have died. American troops then raided homes to detain suspected bomb makers. Also, A US convoy came under rocket-propelled grenade (RPG) attack on Thursday in the town of Fallujah, about75km west of Baghdad, reported Al-Jazeera correspondent. It was not clear whether the occupation soldiers took casualties. Loud explosions were also heard at a US base east of Samarra, 100km northwest of the capital. Troops closed off all roads leading to the area, while helicopters hovered overhead. A number of American troops were injured late on Wednesday when an Iraqi detonated explosives attached to himself at al-Anbar University in the town of Ramadi, Al-Jazeera satellite channel reported. ** More Forces Needed in Iraq, but not Americans*** US Defense Secretary Donald Rumsfeld said Thursday more forces were needed in Iraq but Iraqis and international troops, not more Americans. Rumsfeld's acknowledgement came as he flew to the Middle East on a previously unannounced visit to meet with commanders and troops as the US sought UN backing for a multinational force in Iraq. Speaking to reporters traveling with him en route to the region he acknowledged the need for more security forces in Iraq but said US commanders believe there are sufficient US troops in the country. Rumsfeld said he would be meeting US commanders and civilian leaders in the region to get an assessment of the situation in Iraq where a US-led occupation has been wracked by car bombings, attacks and a mounting coalition death toll. **More British Troops in Iraq*** Defence Secretary Geoff Hoon has ordered a review of British troop levels in Iraq in response to persisting attacks on US and British occupation forces, the Ministry of Defence said Thursday. "In the light of events in Iraq over past weeks, the defence secretary has asked for a review of the forces and resources required to support UK operations," the ministry said. The Daily Telegraph newspaper reported Thursday that Foreign Secretary Jack Straw is pressing for 5,000 extra British troops to be sent to Iraq to avert "strategic failure" of the coalition's efforts to keep peace. **PHOTO CAPTION*** Occupation military police open the door of a mosque during a raid on August 29, 2003 near Baghdad, Iraq. (REUTERS/Robert R. Hargreaves Jr./U.S. Air Force)