Sugar Ray Leonard, the former world welterweight champion who first retired in 1982 after suffering a detached retina, then retired again in 1984 after a shaky comeback bout, said yesterday he would fight again if his opponent were world middleweight champion Marvin Hagler.

"If Hagler called me tomorrow, yes I would fight again . That's why I'm in the gym," Leonard said in an interview with The Washington Post.

"If you have his phone number, have him call me up," Leonard added.

Leonard made his remarks after an unrelated news conference in Mayor Marion Barry's office to announce a May 17 fund-raising dinner for the World Boxing Council's Sports Medicine Foundation.

Leonard said he would not return to boxing to fight anyone else -- only Hagler.

"Every time I see Marvin, I get that itch," Leonard said.

"I have to be honest. I've gotten fighting out of my system, but I would like to fight him. It's something I want to do.

"I don't want to be contradictory. That's why I don't want to say I'm coming back. But if he wants to fight, I'll do it."

Hagler was unavailable for comment, but in Brockton, Mass., Hagler's manager, Pat Petronelli, said, "Marvin would love to fight Sugar Ray. He always has over the years, but something would always come up."

Petronelli said Hagler's camp was "in heavy negotiations" for a possible fight with Thomas Hearns late this year, but that nothing definite had been set with Hearns.

Petronelli said Hagler-Leonard would be a "blockbuster," like the Hagler-Hearns fight of April 1985 when Hagler knocked out Hearns in the third round.

A Leonard-Hagler fight could be the biggest payday in boxing history. At the time of the Leonard-Kevin Howard fight in 1984, speculation had it that a Leonard-Hagler match could result in a $30 million to $40 million total purse.

Hearns, who also has lost to Leonard, said yesterday if Leonard is going to fight, he'd like to be an opponent.

Of Leonard's chances against Hagler, Hearns said: "Now, he doesn't have too much of a chance because he's rusty. He should fight me first before going to Hagler."

Leonard's adviser, Silver Spring lawyer Michael Trainer, said Leonard has "always felt he could beat" Hagler.

"Deep down, he always wanted to fight him," Trainer said. "If he would be given the opportunity, I think he would. I don't think he could turn the challenge down."

Trainer said he has made no attempt to arrange a Leonard-Hagler bout. But he went on to say that Leonard, as a boxing commentator, attends Hagler's fights, and that seeing Hagler up close has reinforced Leonard's belief that he can beat Hagler.

"Every time he comes back from a Hagler fight, there's a lot of anxiety," Trainer said. "It takes him about a month to get over it."

More than a month has passed since Hagler's March 10 11th-round knockout of formerly unbeaten John (The Beast) Mugabi in Las Vegas.

"I think he would get over it this time, too," Trainer said.

But Leonard said he has been getting in better and better condition from working out with Canadian welterweight Shawn O'Sullivan.

"Each time he goes in with Shawn, he would prepare more for it," Trainer said. "It's that pride."

Leonard retired Nov. 9, 1982, after learning he had a partially detached retina of his left eye. He came out of retirement and knocked out Howard, a Philadelphia welterweight, in May 1984 but announced after the fight he would retire for good.

After the fight, in which he was floored for the first time in his career, Leonard said, "There is no sense in fooling myself or anyone else. I've retired. I've officially retired. . . . I can't just go on humiliating myself."

Leonard said yesterday he did not "want to fight just anybody, like a Kevin Howard." But after watching Hagler fight, he said he went home and told his wife Juanita he wanted to fight Hagler. "I've been been training for the past two or three months," he said. "I'm in good shape and my weight has been constant."

Trainer reemphasized what Leonard said, that Leonard would not make a comeback to fight anyone, probably just Hagler.

"The Howard thing was not right," Trainer said. "It was like a step backward. He would never do anything like that again."

Many fight observers believe Leonard would have a difficult time with Hagler. If he had no tuneup fights, which he said he wouldn't need, Leonard would have to come back from a layoff dating to May 11, l984. And that was the only fight Leonard had had since February 1982.

In addition, Hagler, a natural middleweight, would have a distinct size advantage over Leonard. Hagler weighed 159 1/4 for Mugabi; Leonard fought much of his career at 147, although reportedly he has been working out recently several pounds heavier.

Leonard, an Olympic champion in 1976, will turn 30 on May 17; Hagler, according to Petronelli, will be 32 on May 23.

Last year, in what was one of the most publicized fights in history, Hagler (62-2-2, with 52 knockouts) flattened Hearns in the third round after administering a vicious beating.

Leonard, on the other hand, was extended to the 14th round by Hearns in 1981 before Leonard knocked him out.

Leonard (33-1) lost the only fight of his career to Roberto Duran in June 1980 but avenged that defeat with an eighth-round knockout of Duran in November of that year.

Hagler won a decision from Duran in November 1983, the only time since 1980 that Hagler hasn't knocked out his opponent.

Another question about Leonard is the detached retina of the left eye for which he underwent surgery in May 1982. Trainer said yesterday that injury "has been corrected and is fine."

It was not the eye that made him retire, Leonard has said, but a certain feeling during the Howard fight.

"When I got into the ring, it just was not there," he said later. "I didn't feel that drive, the adrenaline flowing. . . . Every round was a struggle. I had to push myself."

But now Leonard insists he is ready to fight Hagler. And with so much money possible from a Leonard-Hagler fight, it's not surprising that Petronelli said Hagler would be eager to fight Leonard.

"Marvin's response would be, Marvin would fight King Kong if the price is right," Petronelli said.

Petronelli added of Leonard, "I've always had a funny feeling he'd be back. He keeps in training, with the Canadian. This is boxing. You never know from one minute to the next. I always felt one day Sugar Ray would fight again."

But Petronelli said that he could make no statement accepting Leonard's "challenge" because of negotiations for another possible Hagler-Hearns bout.

Hagler, meanwhile, "is on a Caribbean cruise," according to Petronelli. To the suggestion that Hagler might not be able to call Leonard immediately, Petronelli said, "News travels fast. There's phones all over."