The Commons public accounts committee has strongly criticised the Ministry of Defence over its decision to purchase eight Chinook helicopters.

Thursday's report said the procurement was "bad decision-making to the point of irresponsibility" and had put the lives of soldiers at risk.

The MPs noted that the MoD has a "history of long delays and cost increases within its procurement projects".

"Even by these standards, the Chinook Mk3 project has been a catalogue of errors from the start," they added.

The original contract was described as "ill-defined" and failed to include easy access to software source code which was vital to enable certification for airworthiness.

Changes to requirements and five years of "protracted negotiation" were then scrapped in 2007, as the MoD came under mounting pressure to provide more helicopters for use in Afghanistan.

That resulted in a new project designed to accelerate the helicopters' entry into operational service.

The cost of the eight Chinook Mk3 helicopters once they enter service will be in excess of £52.5m each, said the MPs.

The committee also suggested that alternatives available at the time of the original order may have been cheaper.

Edward Leigh, chairman of the committee, said the failures had meant a "risk to the lives of British troops".

"The programme was hamstrung from the start by the appalling decision to buy the aircraft without securing access to their software source code," he added.

"This meant that the MoD could not show that the cheaper, modified cockpit avionics which it had chosen met UK airworthiness standards and hence that the helicopters were safe to fly.

"Eight years after they were delivered, the Chinook Mk3s are still sitting in hangers and the cost of getting them into the air is probably going to top £422m, probably by a big margin."

He added that there were still questions over the risk of using the helicopters, warning that there is "a big question mark over whether it is a risk the department should accept".

But defence equipment minister Quentin Davies said the report, the fourth one on the Chinook Mk3 procurement, "offers nothing new".

He noted that the deal was signed in 1997, before the MoD adopted smart procurement.

"This was a very bad case, and I entirely accept the criticism that successive reports have made," he said. "Since then we have fundamentally changed our methods of doing business, but this episode will remain a salutary example to us all."

Davies also defended the decision to convert the equipment for use in a support role. "This will enable us, subject to operational requirements, to increase our Chinook fleet in Afghanistan in 2010 - two years earlier than would otherwise have been possible," he said.