This Little Piggy came right out and said it: "We're engaged."

The roomful of reporters scribbled furiously. The air was suddenly electric.

"That's a blatant lie," Kermit the Frog retorted. "Despite all of the rumors going round, there is no personal involvement between the lady pig and me."

The tension subsided, but the questions continued. What about Miss Piggy's French? She's peppering her sentences with it more and more these days. "How charming of vous," she had purred to Kermit in their first film, "The Muppet Movie," screened a few hours earlier in New York.

"For moi or the frog?" She asked the questioner.

"Most of her French comes off of perfume bottles," Kermit said drawing an icy stare from his porcine companion.

Miss Piggy and Kermit the Frog were on the road promoting their movie, which opened in London last week and will do the same in New York and other American cities on June 22. For their first shot at the big time, they proved able to manipulate an audience as well as the best of the Hollywood glamorosos.

But then Sir Lew Grade (now a lord, but for social purposes only) would expect no less. The international movie mogul, played in the film by Orson Welles as "Lew Lord," spent $8 million to make the movie and will pour another $6 million into its promotion.That's a lot of money, even by his standards, and he wanted his classiest talent out front.

Jim Henson (Kermit) and Frank Oz (Miss Piggy, Fozzie Bear and Animal, among others) are used to it, though. Over the course of the past 16 years, their collaboration has led to international fame and virtually every award available for their line of work. The latest recognition of their talents was an Emmy given to the "Muppet Show" last year as the outstanding comedy-variety or music show.

The statistics are overwhelming, but it suffices to point out that the Muppet Show currently is shown in 106 countries and 156 markets in the United States. Established stars beg to appear on the show, and 15 of then appeared in "The Muppet Movie" in cameo appearances for a fraction of their usual fees. The movie is the latest in a progression of accomplishments which eventually should put the Muppets on par with Micky Mouse.

With talk of a sequel to the movie and accolades everywhere, life is very good for Henson, who first created the precursors to Kermit and Miss Piggy while at the University of Maryland almost 25 years ago. But as he and Oz point out, the future is fraught with the kind of peril that could ruin what made them successful in the first place.

"It's a struggle to keep essence there along with the success," Oz conceded in a serious moment. "I don't want the feeling that the Muppets have lost their innocence."

Innocence is a big part of the Muppet's secret, agreed Henson, the lanky, soft-spoken beard behind Kermit who now lets Miss Piggy do most of the talking. "These characters have to maintain their innocence. That's the essential reason why they work. In the movie, we didn't want the characters to end up rich and famous in Hollywood."

If there is a direct link between trial and reward, Miss Piggy, Kermit, Fozzie Bear, and the other Muppet characters in the movie should all be ensconced in palatial pads in Laurel Canyon by now. Henson's film, directed by James Frawley, is an astonishing amalgam of Pilgrim's Progress, a Hope-Crosby road picture, a Hasty Pudding theatrical, with a "Zorba the Greek" ending.

From the beginning, when Kermit is discovered playing his banjo in a swamp by Agent Dom DeLuise, the word games are relentless. Kermit, who cuts a remarkable figure riding a bicycle, was almost "gone with the Schwinn" when he collided with a steamroller.

The ongoing love affair between Kermit and Miss Piggy could be one of the great screen relationships since Tracy and Hepburn. The candlelight dinner scene between the two, aided by Steve Martin dressed in lederhosen as the waiter, is charming. Martin opens a bottle of Vin de Idaho and allows Kermit to sniff the bottle cap. Unfortunately, Miss Piggy abandons Kermit at this point for her agent, leaving the poor frog alone like Charlie Chaplin in "Goldrush."

"She's in conflict," Oz explained, "She wants the frog, but she also wants her career. She's in a lot of pain."

Oz and Henson agree that the popularity of Miss Piggy has skyrocketed in the past year and overshadowed Kermit in many ways. But both point out that Kermit is one secure frog.

"Kermit is the glue of the show," Oz continued. "The rest of the characters wouldn't be strong without him."

"Kermit is the straight man," added Henson, himself on a far lower key than Oz. "He provides the audience with access to the crazies."

Ultimately, Kermit and friends arrive in Hollywood and make a movie, only to have the roof literally fall in on their set. But a rainbow shines through to the same effect as the dance than Alan Bates and Anthony Quinn performed at the end of "Zorba the Greek." "Life is a movie, and you write your ending," we are told.

The only question at this point is where the Muppets go from here. With Hollywood at their feet, they appear to have run out of challenges. CAPTION: Picture 1, Miss Piggy and Kermit the Frog; Picture 2, Miss Piggy, Frank Oz and Kermit, by Donald F. Holway for the Washington Post