The Veterans Administration is launching a massive review of rejected disability claims following the discovery of 10 million military medical records that duplicate some lost in a 1973 fire.

Veterans groups say thousands of veterans from World War II and the Korean War could be affected by the discovery. They say the newfound records would provide verification for claims denied because there were no records to substantiate them.Thomas K. Turnage, the VA administrator, announced the discovery on Thursday and called it a "very important" development.

"It opens up new vistas for us. It means that these people who before had difficulty establishing a basis for their disability compensation, or the degree of it . . . it means we can have another chance to look at it and, in effect, may come up with a different result," Turnage said.

The VA said that it would immediately begin going through the new data and reviewing claims rejected because of lost records. The agency urged veterans seeking information about their claims to contact their VA regional offices.

Turnage said the VA had become aware of the information last week, and it was too early to say how many people would be affected.

Officials cautioned against overestimating the impact of the discovery. R.J. Vogel, the VA's benefits director, said that most veterans who made disability claims did so during their initial years after service and would likely have filed claims before 1973.

But John Sommer, director of the American Legion Veterans Affairs and Rehabilitation Commission, whose office helps veterans with their disability claims, said there was no doubt the development could affect thousands.

"You'd be amazed at the number of people, World War II veterans in particular, who waited until they retired to file a claim with the VA, and then found the records had been destroyed," he said. "Many of them felt they just didn't want to take anything from the government. ... Then, as they aged, they decided to file a claim and discovered their records had been burned."