MANILA -- As she saunters into her hotel suite, Lea Salonga seems even younger than her 19 years -- small and vulnerable, no one you'd expect to be the focus of what threatens to be a vitriolic international casting battle.

It is only several hours later, before an enthralled audience at her homecoming concert here, that Salonga blossoms, showing why she is the Philippines' most glamorous musical star. Among her recent accolades: Britain's prestigious Laurence Olivier Award this year for Best Performance in a Musical, won for her portrayal of the Vietnamese bar girl, Kim, in the London production of the hit musical "Miss Saigon."

For the former child star, once dubbed "the Shirley Temple of the Philippines," a highly conservative upbringing made the demanding role all the more difficult. At first, she says, the hardest part was "getting over the shock of wearing skimpy costumes and doing love scenes onstage."

Now Salonga's career appears to be facing a much more trying challenge. She is at the center of a new controversy between the American union, Actors Equity, and "Miss Saigon's" British producer, Cameron Mackintosh. The union wants an Asian American to play Kim in the Broadway production of the musical, scheduled to open in April. But Mackintosh this month formally appealed to Actors Equity to approve Salonga, saying he had auditioned 1,200 candidates for the part and found none to match the Filipino star. With the two sides deadlocked, Mackintosh has asked that an arbitrator decide the case, likely to hinge on the issue of whether Salonga is a "star of international stature."

Earlier, Mackintosh and the union had fought over his insistence on retaining British actor Jonathan Pryce in a key Asian role in the Broadway production. The dispute was resolved in the producer's favor amid some bad publicity for Actors Equity, an outcome that Salonga's supporters fear may not augur well for her.

There is a perception that the union's opposition to Salonga "may be a way to get back at Cameron Mackintosh," said Armando Alegre, a leading Philippine impresario who helped supply talent for "Miss Saigon."

Other Filipinos are attaching much broader implications to the dispute, viewing it as one more American slight in the Philippines' long, often troubled relationship with its former colonial patron. Top Manila government officials have expressed support for her, at least one senator has proposed a resolution in her favor, and her father has threatened to return an honorary American flag to President Bush if she is rejected for Broadway.

Feliciano Salonga Jr., a retired merchant marine officer, says the flag was given to the family after having been draped over the coffin of his father, who retired from the U.S. Navy in 1947 after 30 years of service spanning two world wars.

"And now the American Equity is trying to keep a U.S. Navy man's granddaughter out of playing on Broadway -- because she is a Filipina!" the incensed father was quoted saying this week.

"It's sad that some Americans, in a land which has long preached equality of man and equal opportunity, have become such rabid racial bigots," wrote Max V. Soliven, one of Manila's leading columnists.

Disarmingly unpretentious, Lea Salonga herself seems to be taking the fuss in stride.

"It's not the end of the world," she said in her American-accented English as she sat cross-legged on a stool in the Manila Hotel's presidential suite, where the sponsors of her homecoming concerts are putting her up. "If Broadway does happen, then fine, it's great. If it doesn't, I'm not going to be a sourpuss. I'll probably go back to school or continue doing Kim in London. It's really up to me what I want to do."

She leaves no doubt, however, that she wants the part badly -- in part, to help showcase her countrymen's musical talent.

Her performing on Broadway "would mean another chance for the Filipino to get a foot in the door, and hopefully push it open all the way," she said.

In the Drury Lane production of "Miss Saigon" in London's West End, Filipinos accounted for 15 of the 20 Asian performers, out of a total cast of 42. Among them were Victor "Cocoy" Laurel, the son of Philippine Vice President Salvador Laurel, and former Manila rock singer Robert Sena.

Sena sang with Salonga and the 75-piece Philippine Philharmonic Orchestra in her five-show concert series this week, titled "A Miss Called Lea." It was her first appearance here since a brief visit in June to receive an achievement award from President Corazon Aquino.

Onstage, between songs in English and Tagalog, the predominant language in the Philippines, Salonga described her experiences in "Miss Saigon."

To summon the emotion needed to play Kim, Salonga told the audience, she recalled the story of Sisa, the tragic heroine of Philippine independence leader Jose Rizal's 19th-century novel, who went mad after her two sons were killed by the country's Spanish colonizers.

But it was Salonga's singing that Filipinos came to hear, and she thrilled the packed concert hall with a repertoire of show tunes, including her hauntingly beautiful rendition of "I Still Believe" from "Miss Saigon." At the end of her first show, the audience gave her a 10-minute standing ovation.

The concerts were only the latest triumph in a show business career that began at age 6, when Salonga first auditioned for a local production of "The King and I." By 9, she was playing the lead in a Repertory Philippines production of the musical "Annie." In fact the child star, who learned to read when she was 2, memorized the play's entire script, a feat of memory that prompted her director to nickname her "the stage computer."

She made the first of several hit records in the Philippines in 1980, appeared in several other stage productions and eventually was given her own television show, "Love Lea," in 1983.

Last year she enrolled as a freshman in Ateneo de Manila University and began studying medicine. She left school to audition for "Miss Saigon" and has been playing the part in London since opening night in September 1989.

Her long-term ambition? "To finish school," she said, although she no longer wants to study medicine. "The interest is not there anymore." Instead, she eventually would like to teach drama, she said.

More immediately, her focus is still on "Miss Saigon." "Doing Kim on Broadway would be great," she said, a trace wistfully. But "it's completely out of my hands." Her fate rests with her producer, Mackintosh.

"We told him, 'We're leaving everything up to you,' " Salonga said. "If I don't make it, at least I'll know he tried."