John Riggins' bid to regain $300,000 in back salary has been denied by an arbitrator, who found that the Washington Redskins did not improperly prevent Riggins from playing during the 1980 season.

The ruling by arbitrator Bert L. Luskin was made Monday and received yesterday by both the Redskins and the National Football League Players Association, which supported Riggins in his grievance against Washington.

Riggins had claimed that the Redskins barred him from pursuing his livelihood by placing him on the NFL's left-camp retired list Sept. 1, l980. Once placed in that catagory, a player cannot be activated the rest of the season.

Riggins had left training camp in July and asked to have his contract renegotiated, but his request was turned down by the Redskins. He then announced his retirement, although he said in October of that year that he had changed his mind and wanted to play. He later resumed his NFL career during the 1981 season.

Riggins, reached at his home in Lawrence, Kan., refused to comment on the decision, citing his no-interview policy. But Ed Garvey, NFLPA executive director, said that Riggins told him he was relieved "a decision had finally been reached. He took the whole thing very well."

Garvey, however, called Luskin's finding "clearly wrong" and said the NFLPA probably would recommend to Riggins that either Luskin be asked to reconsider or that the case be taken to court. But Garvey admitted that chances of a court reversing the decision would be "very slim," considering the arbitration mechanism is in place in order to negate the need for legal proceedings.

Lawrence Lucchino, Redskins legal counsel, hailed the favorable finding. "We are very pleased," he said. "It's a complete vindication of the positions both the Redskins and the league have maintained. It's important that John's status has been clarified. All's well that ends."

If Luskin had ruled in favor of Riggins, the Redskins possibly could have been directed to pay Riggins his 1980 salary of $300,000. Instead, Riggins now will be entering the option year of his contract. If he and the Redskins cannot reach agreement on a new contract, he will be paid $330,000 for the 1982 season.

"I hope to get in contact with John this week and see what he has in mind," General Manager Bobby Beathard said. "It's good that this has been settled because his contract status has been in limbo for so long. Now we can sit down and make an evaluation of what we think we should offer him."

The long-awaited decision has been delayed for months by Luskin's poor health. He recently underwent bypass heart surgery, the major reason he failed to reach a self-imposed deadline of rendering a verdict by the end of 1981.

Riggins' problems with the Redskins began on July 27, 1980, when he left training camp without explanation after reporting a day earlier and undergoing some mandatory physical tests. He later told the club he wanted the option year of his contract, which then would have covered the 1981 season, changed into a one-year, guaranteed $500,000 pact.

The Redskins, citing club policy, said they would not renegotiate. Riggins said he twice informed the team he was retiring, having lost his "desire" to play. On Sept. 1, when the club had to designate its 45 active players, it decided to place Riggins on the left-camp, retired list to eliminate what then-coach Jack Pardee said was the "lingering doubts about his status. It was affecting the team. So by placing him on this list, we know he won't be back."

The NFLPA and Riggins filed a grievance, claiming two points: the "left camp, retired" designation was not valid since it had not been negotiated through collective bargaining and that the Redskins incorrectly prevented Riggins from resuming his career in 1980.

Luskin denied both claims, in the process voiding the NFLPA's effort to have the "left camp, retired" segment of the NFL constitution and bylaws negated.

Luskin refuted Riggins' claim that he never legally reported to training camp. Luskin also said Riggins was using his training camp boycott as leverage to obtain a new contract and that he retired voluntarily. In the 73-page decision, Luskin repeatedly states that Riggins only once, in October, talked about returning and even then never made a formal request to the Redskins. Otherwise, Luskin says Riggins continually indicated he was happy with his decision to retire.

Riggins, according to Luskin, "knew exactly what he was doing" when he made his decision to leave camp. Wrote Luskin: "John Riggins failed to carry out the terms and provisions of his NFL players' contract in the year 1980 when he asked to be placed in retired status. He was correctly placed in the retired status and he is not entitled to any compensation under terms of his 1980 players contract . . . "

Garvey said he was appalled that so much of Luskin's decision was based on Riggins' lack of public statements concerning his desire to resume playing. "We aren't crying over spilt milk," Garvey said. "We made our best case, we have no complaints there. But this gets my dander up, it really does. It's just wrong. John wanted to play and the Redskins wouldn't let him."