Commissioner Pete Rozelle admitted today that the National Football League is using the lure of expansion to win congressional support for its efforts to gain antitrust law exemption for professional sports.

"If that's dangling, then that's dangling," Rozelle said after conclusion of the annual NFL meetings here. "They (members of Congress) talk to us about expansion. We say that we can't expand without the fear of litigation consequences. If you want to pass this bill, we are now ready to expand."

Rozelle's statements were the strongest indication yet of the league's determination to get approval for its antitrust bill, which would, among other things, void the lawsuit brought against the NFL by Al Davis for preventing him from moving the Oakland Raiders to Los Angeles.

Paul Tagliabue, an attorney for the NFL, said today he expects an antitrust bill to be introduced in the Senate by the end of this week or next. But a spokesman for the Senate Judiciary Committee said nothing was imminent.

"It's just a matter of time," Tagliabue said. "People are still doing their homework. When they finish, something will be introduced."

Tagliabue said he expected joint sponsorship of the bill by members of the Senate Judiciary Committee, but declined to say who those members would be.

A spokesman for the committee, and for its chairman, Strom Thurmond (R-S.C.), said, "Senator Thurmond has talked to both the players and the NFL people and is still studying the question and has not yet made up his mind what he's going to do. We don't know of any other senator who is imminently about to introduce something."

The NFL wants to see a bill introduced that would allow the league to be treated as a single entity for the purposes of deciding where to locate teams and what kind of ownership standards it wants.

The rights of the players union under antitrust and labor laws would remain unchanged, Tagliabue said.

The NFL Players Association has accused the league of also wanting to use the bill to break the union and to pave the way toward moving games from commercial to pay television. The union has devoted much time to lobbying Capitol Hill in opposition to the legislation.

"The bill won't pass," Ed Garvey, executive director of the NFLPA, said. "It's that simple."

Players unions in baseball, basketball and hockey today condemned the effort to exempt professional sports from antitrust laws. Larry Fleisher, head of the pro basketball players' union, said the groups sent a telegram to members of the House and Senate judiciary committees, urging them not to sponsor a bill.

"Such a bill is not even deserving of consideration by Congress or any other committee of Congress," the telegram said.

Rozelle has said the bill will be designed specifically to make sure it does not affect the ability of the union and individual players to sue the league.

Instead, he said, the league is seeking protection from suits by member teams and cities over internal decisions by the NFL.

"All we want is a bill that gives us the same antitrust liabilities as any multidivisional corporation such as Ford or McDonald's," Rozelle said. "We get that bill and we'll appoint an expansion committee and we'll look at all the cities that are interested in a team. It's been six years since Tampa Bay and Seattle, and we are ready to expand, but we are not going to do anything that will lead to more litigation."

Indianapolis, which is about to build a domed stadium, and Jacksonville, which is expanding the Gator Bowl's seating capacity, had delegations at this meeting to promote their cities for franchises. Phoenix wants a team, as does Memphis, where hopes are being bolstered by Sen. Howard Baker (R-Tenn.), the Senate majority leader.

The antitrust bill has become the NFL's top priority, exceeding even the ongoing negotiations with the NFLPA over a new collective bargaining agreement.

Rozelle also said:

* He took seriously the NFLPA's threat that it would consider forming a new league if the players were locked out of training camp this summer. But he said he felt it would take at least a year to get a new league started.

* He wasn't sure what he would do after his contract as commissioner expires in five years.

In other matters, the league competition committee approved some minor rule changes, including the elimination of the prohibition on offensive double shifts within an opponent's 20-yard line and the elimination of a little-known rule that gave coaches the right to mutually agree to end a game.