Head of the International Atomic Energy Agency (IAEA), Mohammed el-Baradei, on 5 May warned that some of Iraq's nuclear sites had been looted of dangerous materials, and called for the agency to be allowed in to conduct inspections. 'We have been assured by the US that they would secure these facilities, but the agency finds these reports [of looting] disturbing,' IAEA spokesman Melissa Fleming told the BBC. She said that a letter had been sent to this effect to US Secretary of State Colin Powell, but had elicited no response. Radioactive material has reportedly been taken from the Baghdad Nuclear Research Facility and no action has been taken to secure the large Tuwaitha site, south of Baghdad. The agency fears that material from these sites could be used to make a 'dirty bomb' and at the very least would pose health and environmental risks. State Department spokesman Richard Boucher dismissed the reports of looting and the concomitant risks. 'Coalition forces have secured the facilities that house the natural and low enriched uranium that was at those sites,' he said. 'All of this uranium would require significant processing in order to be suitable for enrichment for weapons use.' Boucher said that no decision had yet been made on what role the IAEA might play in post-war Iraq.