Negotiators for the National Football League and the striking NFL Players Association returned to the bargaining table today after a week's recess. Meetings continued into Sunday.

However, there were no signs that an end to the 40-day old walkout was in sight and there appeared to be no significant shift in either side's position.

Mediator Sam Kagel, who sent union and management negotiators home last Saturday after 12 days of trying to mediate a settlement in Cockeysville, Md., convened the players and management shortly after noon today in the top floor penthouse conference room of the Summit Hotel in midtown Manhattan.

As he did during the 12 days of mediation in Cockeysville, Kagel immediately announced he was imposing a news blackout for the duration of the talks.

"With all due respect to the media, this matter cannot be settled in the media," said Kagel, 73, a lawyer from San Francisco and a veteran arbitrator of labor disputes. "It must be settled directly by the parties involved."

Kagel said the only authorized comments on the status of the negotiations would be his own, and he said all his statements would be cleared in advance with each side.

As the nation's football fans faced their sixth consecutive Sunday without NFL games, both sides were predicting a new offer from the other. Both sides also denied they were prepared to put anything new on the table.

"We are ready to respond to any offer they put on the table," said the union's president, Gene Upshaw of the Los Angeles Raiders, at a news briefing before the talks began.

But Upshaw added that to be acceptable to the players, any management offer must address five major player concerns: protection for the older players from being cut for economic reasons, a guarantee of a fair share of future television revenues, elimination of wage inequities, performance-incentive bonuses and immediate and substantial pay raises for all players.

The players have proposed establishment of a trust fund from which players would be paid on a seniority-based scale with performance-incentive bonuses to meet those concerns, but in the last few weeks they have said they would move away from that concept if NFL management could find another way of meeting their concerns.

"Any offer that is put on the table has to respond to the five points," Upshaw said. "That is our position and that will be our position. The issue is collective bargaining versus individual negotiations."

Despite repeated reports to the contrary, however, management continued to insist that no new offers would be forthcoming in this round of negotiations.

Meanwhile, Dave Sheridan, a union spokesman, said most, if not all, of the NFLPA's 28 player representatives are en route to New York to monitor the progress of the negotiations. "They were very concerned about the negotiations," he said. "We thought it would be a good idea to get them all here. This is a crucial time in the negotiations."

Six games of the 16-game regular season already have been called off because of the strike. Management is known to feel there must be a settlement within a matter of days in order for the players get back to practice facilities in time for next weekend's games if a 12-game season is to be salvaged. Many of the owners feel that is the minimum number of games necessary if the season is to maintain its credibility. Two of the called-off games could be made up, the NFL says.

However, Ed Garvey, executive director of the NFLPA, noted that the NFL's chief labor negotiator, Jack Donlan, has agreed that the number of poststrike games to be played is a subject to be resolved at the bargaining table.

As the talks were resumed today, Kagel met first in his suite with Garvey and Donlan for two hours; then recessed for an hour and then met with Garvey, Donlan, Upshaw and Sargent Karch, the general counsel for the NFL Management Council, the league's labor negotiating arm.