Negotiations between the Washington Redskins and running back Mike Thomas continued today in Washington, and a team source said good progress was being made and an agreement probably will be reached by the end of the week.

Guy Draper, the agent representing Thomas, met with team president Edward Bennett Williams and Tim Temerario, the club's negotiator, at Williams' downtown office this afternoon for two hours.

The Redskins reportedly have offered Thomas a contract in the $120,000 range for the 1977 season. A year ago, Thomas gained more than 1,000 yards and was paid approximately $30,000.

In training camp, the Redskin injury list grew. Center Ted Fritsch left the field after twisting his knee and fullback Willie Spencer apparently aggravated a muscle pull he suffered last week. Neither injury is serious, but both players probably will miss several days of practice.

Redskin coach George Allen also indicated today that he had not made up his mind to start Billy Kilmer at quarterback Monday night in the preseason opener against the Browns. Kilmer is recovering from a sore right arm.

"I'm going to talk to him and see how he feels," Allen said. "I don't want to push him in there. It's a six-game preseason and if he missed a game, it wouldn't hurt him at all. The big thing is for him to get 100 per cent."

If Kilmer does play - and the way Allen is talking he probably won't - he would only see about a quarter of action, with Joe Theismann handling the rest of the work.

Allen took some of the burden off his quarterbacks today by again signing 26-year-old Jerry Trooien, who reported to camp three weeks ago and failed his physical.

Allen said Trooien signed a waiver that would relieve the club of responsibility if he was injured, and reported for the afternoon practice. He will probably stick around until the first major cut on Aug. 9.

Offensive tackle Tim Stokes also took part in his first workouts. He reported late Tuesday night, Allen has him running on the second-team line and said he probably would not be used Monday against the Browns, although Stokes tied a lineman's record of running 6 1/2 laps in 12 minutes this morning.

Allen most likely will start Terry Hermeling at left tackle and Dan Nugent at right guard in Cleveland. Stokes should return with the first unit next week, and Hermeling will switch back to starting right guard.

Pat Fischer is resting a sore back and missed both workouts today, and Dennis Johnson has been hobbled by a slight groin strain . . . Receiver Brian Fryer has been advised to stay off his puffy right knee for a week to 10 days; there is a possibility he has a slight tear in the cartilage. It was incorrectly reported in Wednesday's editions that Pryor underwent knee surgery last year. He suffered a sprained knee but no operation was required. The Washington Post regrets the error.