A batch of high-tech military helicopters has been out of service for eight years in one of the British military's costliest procurement blunders.

The eight Chinook Mk3s cost 259 million pounds but have been in storage since they were delivered in 2001 because of software problems.

The Times of London newspaper reported Tuesday that the problem was caused when officials tried to save money by installing their own avionics software rather than using the kind supplied by manufacturer, Boeing. It cited an unidentified "defense insider."

The Ministry of Defense denied that it had been trying to save money. But it did acknowledge the order had been bungled.

In a report last year, the National Audit Office found that British officials had failed to ask for the access code for the software when they ordered the helicopters. That code was needed to test that the helicopters met British defense safety standards.

Boeing refused to hand the code over once the mistake was noticed, citing intellectual property rights.

Recriminations over the bungled Chinook order have rumbled on for years. In 2004, the head of the House of Commons Public Accounts Committee said the contract was "one of the most incompetent procurements of all time."

Officials estimated last year that the years of delay had raised the cost of the helicopters to 422 million pounds.

The military eventually gave up on trying to fix the software problems and refitted the mothballed helicopters to the standards of an earlier Chinook model for use as support aircraft. They are due to go into use over the next year, bringing Britain's Chinook fleet to 47.

Army commanders and opposition politicians say the British military needs more helicopters in Afghanistan, where troops are increasingly being killed by roadside bombs.