The National Football League yesterday opened the way for returning players to compete with replacement players for jobs when the owners' Management Council announced that, effective Tuesday, rosters will be increased from 45 to 85 players.

Teams still will only be able to dress the prestrike roster limit of 45 players for games next weekend. But they can carry a 40-man inactive roster, or taxi squad, and activate any of those players up until five minutes before game time. Rosters will be reduced the following week, but will remain "substantially more than a total of 49 for some period of time," according to Eddie LeBaron, a Management Council official.

All 85 players will be paid regular salaries, said John Jones, a spokesman for the Management Council.

In another development, the National Labor Relations Board said it did not have enough time to intervene immediately and attempt to allow regular players to compete in this weekend's games. The NFL Players Association had asked for help in getting its members on the field after they ended their 24-day strike on Thursday but were told by management that, instead, replacements would be used for a third straight week.

The NLRB said it did not have enough time to complete an investigation and seek injunctive relief.

Dick Berthelsen, general counsel for the NFLPA, said the union has asked the NLRB to seek an injunction enjoining the NFL from counting this week's games in the standings because of the effect it would have on determining playoff berths and possible monetary losses by the returning players. The union also wants to recover this week's salaries for the players, totalling about $20 million.

With the increased rosters, the NFL careers of many replacement players will be extended. They will compete against returning players for jobs and they will serve as insurance in case of another walkout by returning players, who returned without a new collective bargaining agreement or a back-to-work agreement.

The Management Council did not issue its memorandum notifying clubs of the increased roster limit until late in the afternoon. Many club executives were expecting only a small increase in game rosters, from 45 to 49.

"I'm surprised at the size, but it's great," said Bobby Mitchell, a Redskins assistant general manager. "It gives us time to look at the young guys. It gives the kids a chance to assimilate with the veterans. It give them a fair shot to make the team."

The greatly expanded rosters didn't surprise Berthelsen. "They obviously fear some kind of walkout and they're doing this for the same reason they had so many players in camp this summer," he said. "At least we've created new jobs."

Just because they'll be on the same field as the replacement players doesn't mean some returning players will consider them teammates, according to Redskins defensive tackle Dave Butz. "I doubt if I'd talk to them," he said.

Mitchell said the players would have to practice together. "They'd have to. We're all one now."

Redskins lineman Jeff Bostic called the expanded rosters "an owners' insurance policy. {But} going back out is not even a consideration of ours."

The additional roster spots will cost the owners about $180,000 a week, based on an estimate by M.J. Duberstein, NFLPA director of research, who also estimated that teams saved almost $2 million in salary costs for the three replacement games.

"I don't mind as long as it helps us toward Super Bowl XXII," said Redskins owner Jack Kent Cooke when asked about paying as many as 85 players, not including those on injured reserve.

The final roster size probably will be determined at a league meeting scheduled for Kansas City Oct. 27, according to the Associated Press.

Tex Schramm, a member of the Management Council's executive committee and president of the Dallas Cowboys, said it was likely the owners would decide to keep the active roster at 45, but that a "reserve squad" might be added so that coaches could keep replacements who had been impressive.

NLRB agents took statements from representatives of both the players union and the NFL yesterday concerning the Management Council's decision to stand firm on its 1 p.m. Wednesday deadline for striking players to be eligible to play and receive a paycheck.

"The information we have now is insufficient to procede into court seeking an injunction," an NLRB source said.

The NLRB usually conducts a thorough, sometimes lengthy, investigation before seeking injunctive relief in a federal court, the source said, adding the NFLPA couldn't present enough evidence to warrant such an extraordinary remedy as an immediate injunction.

Jim Conway, general counsel for the Management Council, said that the owners' decision was based on "valid football- and business-related reasons" and what he said were previous NLRB decisions that allow employers up to five days after reinstatement before putting workers back on the job.

Jim Kensil, president of the New York Jets, said the owners were within labor law on not using or paying regular salaries to the players this week because "it's in the absence of an agreement."

The players will continue to be covered under terms of the 1982 collective bargaining agreement.

Berthelsen stressed that the union will press on, even though it was unable to get an immediate injunction. "We will still be going for injunctive relief as soon as possible, to have the court enjoin the NFL from counting Sunday's games in the standings," he said.

Meanwhile, Gene Upshaw, executive director of the players union, told United Press International that despite criticism from some players and the fact that the strike ended without a new collective bargaining agreement, he would not step down.

"I'm not resigning at all," he said. "Gene Upshaw will be the executive director of the players association until the players decide they don't want Gene Upshaw as executive director. Right now, I have a contract and I'll be there."

Staff writer Christine Brennan contributed to this report.