DETROIT — A defiant Chrysler is refusing to recall about 2.7 million Jeeps the government says are at risk of a fuel tank fire in a rear-end collision.
The National Highway Traffic Safety Administration sent Chrysler a letter asking that the company voluntarily recall Jeep Grand Cherokees from 1993 through 2004 and Jeep Libertys from 2002 through 2007.
Chrysler Group, majority-owned by Italy’s Fiat SpA, said in a statement Tuesday that the Jeeps are safe and it ‘‘does not intend to recall the vehicles.’’
Such a refusal by an auto company is rare. NHTSA can order a recall but needs a court order to enforce it.
David Strickland, the agency’s administrator, said in a statement that he hopes Chrysler will reconsider its decision. ‘‘Our data shows that these vehicles may contain a defect that presents an unreasonable risk to safety,’’ Strickland said.
NHTSA opened an investigation into the Jeeps in August 2010 at the request of the Center for Auto Safety, a Washington, D.C., advocacy group. Clarence Ditlow, the center’s director, has repeatedly sent letters to Chrysler seeking a recall.
The agency found that the Jeeps’ fuel tanks can fail when hit from behind, leak fuel, and cause fires if there is an ignition source. The placement of the tanks behind the rear axle and their height above the road is a design defect, NHTSA wrote in a letter to Chrysler.
Chrysler moved the fuel tanks on the Grand Cherokee ahead of the rear axle in 2005, and did the same thing with the Liberty in 2007. But retrofitting the older Jeeps would be time consuming and costly. In 2011, when Toyota recalled 1.7 million cars for possible fuel leaks from loose fuel pressure sensors, an analyst estimated the cost at $240 million.
Automakers usually agree to a recall request, partly to avoid bad publicity. In the last three years, Chrysler has conducted 52 recalls.
Chrysler says its review of nearly 30 years of data shows a low number of rear-impact crashes involving fire or a fuel leak in the affected Jeeps.
But NHTSA said the older Jeeps performed poorly when compared with all but one similar vehicle from the 1993 to 2007 model years, ‘‘particularly in terms of fatalities, fires without fatalities, and fuel leaks in rear-end impacts and crashes.’’
NHTSA found at least 32 rear-impact crashes and fires in Grand Cherokees that caused 44 deaths. It also found at least five rear crashes in Libertys, causing seven deaths.
NHTSA asked Chrysler to recall the vehicles and ‘‘implement a remedy action that improves their performance in rear-impacts and crashes.’’ It made no recommendation on a fix.
The dispute leaves owners of the affected Libertys and Grand Cherokees waiting for government or court action.
It also leaves Chrysler open to the risk of big liability if there are more crashes and injuries linked to the fuel tanks, said Logan Robinson, a University of Detroit Mercy law professor and former Chrysler corporate counsel.
NHTSA concedes that point, but says the standards are minimums for vehicle safety. ‘‘The existence of a minimum standard does not require NHTSA to ignore deadly problems,’’ the letter said.
Chrysler has until June 18 to respond to the letter. If it formally decides against a recall, the company must explain the action to NHTSA, and the agency can then issue a final decision that the Jeeps are defective.