Leonard Tose, the debt-ridden owner of the Philadelphia Eagles, relented to building pressures last night and announced that his team will not move to Phoenix. Tose said he has accepted a package of stadium improvements and financial concessions that will keep the team in the city it has been in since the NFL franchise was founded in 1933.

"I'm very pleased tonight because the Eagles will be staying in Philadelphia where they belong," Tose said at a late-night joint press conference with Philadelphia Mayor W. Wilson Goode at City Hall.

Under the deal negotiated yesterday with city officials, Tose will remain in control of the franchise, although that insistence cost him a $42 million package of loans and refinancing that the city's major lending institutions were willing to give him. Instead, the city agreed to some stadium enhancements, and Tose's financing will be discussed by the NFL at a special league meeting in New York Tuesday to study the Eagles' situation and the issues it raised.

There were indications last night that the NFL would back as much as $12 million in loans to Tose.

Tose is reported to be $40 million in debt. He said earlier this week that he wanted to remain in Philadelphia, but had to deal with the Phoenix interests in order to survive.

Goode said the city agreed to add at least 50 luxury skyboxes, add other boxes and install escalators. Further, the Eagles' $800,000 annual rent at Veterans Stadium will be deferred for an unspecified period. The city also will build the team a new practice facility at an unspecified site, promote the team, reduce its share of parking revenues to match its arrangement with the baseball Phillies and add security for games.

For their part, Goode said, the Eagles agreed to extend their lease at Veterans Stadium for 10 years, through the 2011 season.

Goode declined to say how much the deal would cost the city, saying he would issue a more detailed statement Monday. He did say, however, "The benefits will far outweigh the costs."

Such a deal as announced last night would give Tose additional cash flow and apparently enable him to get loans or refinancing outside the Philadelphia area. On Friday, Tose and the city's major lending institutions had reached a stalemate in negotiations for a $42 million package of loans and refinancing because Tose would have been forced to give up managerial control of the team and serve only as a figurehead.

"I have talked to Commissioner (Pete) Rozelle, and he has promised his complete cooperation, which I appreciate. Throughout these difficult negotiations, my foremost desire has been to keep the Eagles in Philadelphia," Tose said.

"At the same time, I wanted to remain an active part of the team that means so much to me," Tose said. "I never wanted to put Eagles fans, Mayor Goode or any other person in Philadelphia through the tribulations of this week. But the financial negotiations were so complex that they couldn't be completed quickly."

The announcement came five days after a team spokesman confirmed that Tose was considering sale of 25 percent of the team to James Monaghan, a Canadian real estate developer who lives part-time in Phoenix, and move the club there.

There was no immediate response from Monaghan or Phoenix officials last night. Tose said he had not talked to Monaghan since making his decision.

But it seemed certain that Tose knew he would be in for lengthy, expensive litigation from both the NFL and the City of Philadelphia if he attempted to move the team. He would also have faced pressure from Congress to block the move.

Earlier in the day, the Arizona State University board of regents gave the university the go-ahead to begin dealing with the Eagles for a lease at Sun Devil Stadium in Tempe, but there were signs all day that the team was likely to stay put. For instance, Sen. Arlen Specter (R-Pa.) said in Philadelphia, "Obstacles are building against the transfer, so momentum is building in the other direction."

Also earlier yesterday, Goode said for the first time that the city would sue Tose and the Eagles for breach of contract if they left. Goode said the Eagles had been obligated to play in Veterans Stadium until 2001.

On Friday, the NFL filed a civil complaint in U.S. District Court in Philadelphia asking the court to enforce the Eagles' contract to be the NFL team in Philadelphia. The NFL also asked the court to rule that the league has the legal power to require teams wishing to move to justify their request.

The league considers such a ruling on the antitrust issue vital in view of court decisions in the Los Angeles Raiders case that struck down the NFL rule on franchise relocation. Although pro basketball and soccer have changed their rules concerning franchise shifts as a result of the Raiders case, the NFL contends it is powerless to stop franchises from moving. The NFL took no vote when Robert Irsay vanned his Colts from Baltimore to Indianapolis.

NFL owners and officials, who may have to pay the Raiders $49 million in damages, have said they are gun-shy about the prospects of another owner taking the league to court and winning a $50 million suit. But Specter, a former antitrust lawyer, said, "They (the NFL lawyers) are overly cautious in their approach. I think they hold out hope of winning the Raiders case (in another appeal to the Supreme Court after an appeals court rules on the damages) which is between slim and none. They don't read it different."

The NFL suit against Tose and the Eagles also serves to protect the league in defense of the U.S. Football League's $1.2 billion antitrust suit that charges the NFL with conspiring to put the 2-year-old USFL out of business. It argued that it was a renegade owner, not a league conspiracy, looking to move into USFL Arizona Outlaws territory.

Specter and other legislators are putting pressure on the NFL "to adopt a rule which would establish standards for a team move and would require a simple majority vote of the owners to allow that move under the application of the standards," Specter said in a letter he sent to Rozelle last week.

"If they do that, Tose will know he's had it," Specter said in a telephone interview yesterday.

In the letter, Specter wrote Rozelle that "if the NFL were to adopt such a rule in response to the Raiders' court decisions and the moves of the Colts and the prospective move of the Eagles, it is my thought that the Congress would be very sympathetic to legislation which would make it plain that such a rule did not violate antitrust laws.

"When considering that rule, I think the Congress would also be favorably disposed to "sprinkling holy water . . . on some of the other rules which the NFL needs for the orderly processing of its business."