US officials have criticised chief weapons inspector Hans Blix's failure to mention the discovery of a banned Iraqi aircraft in his report to the UN Security Council on 7 March. The discovery of the unmanned aircraft or remote piloted vehicle (RPV), made on 4 March, was revealed in a document circulated among Security Council members entitled 'Unresolved Disarmament Issues: Iraq's proscribed weapons programmes'. However, in his verbal report, Blix merely said that inspectors had raised the matter of RPVs with Baghdad, without giving details of the find. Inspectors, making an unannounced visit to the Samarra East flight-test facility north of Baghdad, found the Iraqis in the process of dismantling an RPV with a range far above that allowed under UN rules. The fear is that such vehicles could be used to drop chemical and biological agents. In a 10 March UN Security Council session, US ambassador John Negroponte called the RPV part of a 'linear development' towards Iraq obtaining chemical and biological weapons capabilities and a 'serious violation' of UN resolutions.