WASHINGTON – Hundreds of U.S. Marines have been killed or injured by roadside bombs in Iraq because Marine Corps bureaucrats refused an urgent request in 2005 from battlefield commanders for blast-resistant vehicles, an internal military study concludes.

The study, written by a civilian Marine Corps official and obtained by The Associated Press, accuses the service of “gross mismanagement” that delayed deliveries of the mine-resistant, ambush-protected trucks for more than two years.

Cost was a driving factor in the decision to turn down the request for the so-called MRAPs, according to the study. Stateside authorities saw the hulking vehicles, which can cost as much as a $1 million each, as a financial threat to programs aimed at developing lighter vehicles that were years from being fielded.

After Defense Secretary Robert Gates declared the MRAP (pronounced M-rap) the Pentagon’s No. 1 acquisition priority in May 2007, the trucks began to be shipped to Iraq in large quantities.

The vehicles weigh as much as 40 tons and have been effective at protecting American forces from improvised explosive devices (IEDs), the weapon of choice for Iraqi insurgents. Only four U.S. troops have been killed by such bombs while riding in MRAPs; three of those deaths occurred in older versions of the vehicles.

The study’s author, Franz J. Gayl, catalogs what he says were flawed decisions and missteps by midlevel managers in Marine Corps offices that occurred well before Gates replaced Donald Rumsfeld in December 2006.

Among the findings in the Jan. 22 study:

• Budget and procurement managers failed to recognize the damage being done by IEDs in late 2004 and early 2005.

• An urgent February 2005 request for MRAPs got lost in bureaucracy.

• There was more concern over how the MRAP would upset the Marine Corps’ supply and maintenance chains than there was in getting the troops a truck that would keep them alive.

• The Marine Corps’ acquisition staff didn’t give top leaders correct information.

• The Combat Development Command, which decides what gear to buy, treated the MRAP as an expensive obstacle to long-range plans for equipment that was more mobile and fit into the Marines Corps’ vision as a rapid reaction force.

Gayl, who has clashed with his superiors in the past and filed for whistle-blower protection last year, uses official Marine Corps documents, e-mails, briefing charts, memos, congressional testimony, and news articles to make his case.

He was not allowed to interview or correspond with any employees connected to the Combat Development Command. The study’s cover page says the views in the study are his own.

Maj. Manuel Delarosa, a Marine Corps spokesman, said it would be inappropriate to comment on it.

The study does not say precisely how many Marine casualties Gayl thinks occurred due to the lack of MRAPs, which have V-shaped hulls that deflect blasts out and away from the vehicles.

Gayl cites a March 1, 2007, memo from Conway to Gen. Peter Pace, then the chairman of the Joint Chiefs of Staff, in which Conway said 150 service members were killed and an additional 1,500 were seriously injured in the prior nine months by IEDs while traveling in vehicles.

The MRAP, Conway told Pace, could reduce IED casualties in vehicles by 80 percent.

Congress has provided more than $22 billion for 15,000 MRAPs the Defense Department plans to acquire, mostly for the Army. Depending on the size of the vehicle and how it is equipped, the trucks can cost between $450,000 and $1 million.

As of May 2007, roughly 120 MRAPs were being used by troops from all the military services, Pentagon records show. Now, more than 2,150 are in the hands of personnel in Iraq and Afghanistan. The Marines have 900 of those.

A former Marine officer, Gayl spent nearly six months in Iraq in 2006 and 2007 as an adviser to leaders of the 1st Marine Expeditionary Force.