A Democratic senator charged yesterday that "lives are being lost" because the Reagan administration has "refused to implement" a law requiring the creation of a nationwide computer network to match people who need transplants with available organs.

"This law is not being implemented by the administration," said Sen. Albert Gore Jr. (D-Tenn.) at a news conference held one year after the National Organ Transplant Act was signed.

"Their foot-dragging in implementing the law, and their continued insistence that voluntary groups and private organizations can solve this societal problem -- a problem that requires a national solution -- is inexcusable and indeed a great tragedy for thousands of families around the country," Gore said.

The Health and Human Services Department, however, disputed Gore's charges. Linda Sheaffer, acting director of the Office of Organ Transplantation, said a task force established by the law had met six times and on Oct. 1, unanimously adopted recommendations for creating the network.

She said specifications for the computer contract are being drawn and she hopes the contract will be awarded by early next year.

Gore aides said, however, that the law anticipated that the contract would be awarded much sooner, without having the task force draw up guidelines. The aides said that at the senator's request, the report on the HHS appropriations bill instructs the department to award the contract by Dec. 15.

Joining Gore in a call for swifter action were Dr. Anthony P. Monaco, president of the American Society of Transplant Surgeons, and Charles Fiske, whose dramatic plea to the American Academy of Pediatrics' 1982 annual meeting for a liver for his infant daughter Jamie was televised nationally.

Fiske said his daughter had survived because a couple whose child was dying after an auto accident had seen his plea and donated their child's liver. But he said people like him "should not have to turn to the media" in each individual case.

Gore urged the administration to accept a recommendation to allow Medicare to pay for heart transplants for disabled persons under 55 who are covered by Medicare.