Iraqi resistance fighters attacked a US convoy with a rocket-propelled grenade in Tikrit on Wednesday, killing a translator for the occupation forces and injuring two occupation soldiers, said US army officials. The attack took place shortly after noon. The soldiers were traveling in a three vehicle convoy in the Tikrit market district. **Grim Task of Combing UN HQ Wreckage for Dead*** More bodies are likely to be pulled from the rubble of the United Nations headquarters in Baghdad after Tuesday's devastating bomb. At least 20 people have already been confirmed dead, among them the UN's top diplomat in Iraq, Sergio Vieira de Mello. Meanwhile, the US Federal Bureau of Investigation is building up a picture of exactly what happened. The senior FBI officer in the capital said human remains had been found inside the lorry carrying the bomb, indicating a suicide attack. He also said the bomb consisted of nearly 700 kg of explosive, as well as artillery and mortar shells. The UN has suspended operations in Baghdad. Arrangements are being made for staff who want to leave while others are being told to stay in their lodgings. The explosion has prompted a further review of security in Baghdad. Extra measures are being taken at the British embassy to protect the compound as best possible from a similar attack. This latest deadly bombing, coming soon after attack outside the Jordanian embassy that killed 17 people, is another serious blow to the morale of international workers and local people working with them. **Annan vows UN "Will not be Deterred" in Iraq*** UN Secretary General Kofi Annan, travelling back to New York, has paid tribute to the Baghdad bombing victims. He stressed they were in Iraq to help the population: "Yesterday was a dark Tuesday for the UN, for Iraq and for international solidarity. On that day the UN lost some of its most outstanding public servants especially Sergio Vieira de Mello who was really the most brilliant colleague, our brightest and best, and many others were injured." Annan insisted UN staff would remain in Iraq, saying the organisation would not be intimidated. He said the UN would undertake a comprehensive re-assessment of security arrangements. The UN Staff Council's security committee called on Annan "to suspend all operations in Iraq and withdraw its staff" until security was improved. It demanded a "full investigation" to determine why adequate security was not in place. Annan accepted that the US-led coalition was in overall charge: "When you have this kind of terrorist attack, you don't know where it is going to come from and I'm not sure one can entirely protect against it. But in the broader sense, securing the environment is the responsibility of the coalition." **PHOTO CAPTION*** U.S. soldiers guard the United Nations headquarters Wednesday, Aug. 20, 2003. (AP Photo/Manish Swarup)