The US military in Iraq has lost track of another 12,000 weapons, including more than 800 machine-guns, and everything from 2100 new electricity generators to half a dozen garbage trucks.

The latest gap in record-keeping follows a report by the US government's accountability office in the summer which revealed that 190,000 Kalashnikov assault rifles and automatic pistols earmarked for Iraqi government forces had gone astray in 2004 and 2005 and could be in insurgent hands.

The US Defence Department said an audit between March and May this year could trace only £41m-worth of armoured vehicles and other equipment worth more than £500m which was supposed to be part of Iraq's police and army training and outfitting package.

Items which had disappeared without leaving a paper trail included 2300 rocket-propelled grenade launchers, 7000 pistols and 18 heavy recovery vehicles worth £5m.

More than 2100 of 2900 electricity generators - scarce and expensive in a country where mains supplies have become erratic - have also vanished. They cost £3.5m to buy.

Six modern garbage trucks from a delivery of 18 on Baghdad's rubbish-strewn streets could not be located. They were valued at £350,000.

The auditors said that the Multi-National Security Command Iraq could not give reasonable assurance that money for the Iraqi forces was being used properly and properly protected from "waste and mismanagement".