A congressional report due for release next week says there is apparent widespread and growing abuse - running into millions of dollars - in the program Uncle Sam uses to compensate workers injured or disabled on the job.

The General Accounting Office study says the number of federal and postal employes applying for disabilty compensation has increased by nearly 10 times in the past five years. It suggests that many civil servants may be abusing the system which was liberalized in 1974, and may be faking serious injuries as a way to get more paid time off.

GAO made the investigation at the request of Rep. Don J. Pease (D-Ohio). Pease believes that liberal federal rules, which allows claimants to draw full salary for 45 days after an injury, encourage some employes to abuse the system.

Pease's office confirmed that the GAO report was made for them, and that it does show a "dramatic" jump in the number of claims in recent years although the size of the federal work force has remained relatively stable. Pease said the government paid out $267 million in 1974 for claims for job-related injuries, and that dollar amount rose to $552 million in only three years.

The number of claims has risen from 12,000 in 1974 to the present level of more than 100,000 a year. Pease plans to make details of the GAO report, and his recommendations for a tightening of the compensation program, public at a press conference next Monday.