Don Weiss, executive director of the National Football League, said today the Philadelphia Eagles have asked the league security department to help them investigate the case of "someone" sending a copy of the club's playbook to Coach Tom Landry of the Dallas Cowboys.

Owner Leonard Tose of the Eagles said on Sunday in St. Louis that Landry called Coach Dick Vermeil on Thursday and reported he had been mailed a Philadelphia playbook and would send it to Vermeil.

Tose reported that Landry said he had received the playbook "about two weeks ago."

Weiss, in a telephone interview, was asked why Landry took so long to call the Eagles, whether any of the Eagles had reported losing a playbook, and whether any other clubs reported being sent a copy of it.

"In any of these investigations, we don't discuss details until we know the facts," Weiss said. "We are looking into the case."

The NFL would seem to have a public relations problem on its hands if copies of the playbook have been sent to other clubs and they have not reported it to the Eagles or to the league.

Those clubs would be taking the risk that the person who might have sent copies of the playbook would identify them as covering up, and thus damage the league's image of integrity.

Weiss said he didn't know if Landry had been consulted or whether he might face disciplinary action if indeed he was dilatory in reporting receipt of the playbook.

The Cowboys will play the Eagles for the first time this season in Philadelphia Oct. 19.