UPDATE 2-'Bruno' fashions top spot at U.S. box office

* "Bruno" leads North America, U.K. and Australia

* "Transformers" soars to $339 million in North America

* "Ice Age" top film overseas (Adds big drop for "Bruno," foreign sales for "Ice Age" and "Transformers" in paragraphs 3-6)

LOS ANGELES, July 12 (Reuters) - "Bruno," British satirist Sacha Baron Cohen's latest subversive outing, narrowly claimed the No. 1 spot at the weekend box office in North America, according to studio estimates issued on Sunday.

The "mockumentary," in which Baron Cohen plays a gay Austrian fashion model seeking fame in the United States, sold $30.4 million worth of tickets during the three days beginning July 10, distributor Universal Pictures said.

But the film lost 39 percent of its audience from Friday to Saturday, a hefty drop given that movies usually see an uptick in that period.

Rival studios pounced on the slide, forecasting "Bruno" would have a short run in theaters. But Universal distribution president Nikki Rocco said such a dip "was not unusual in summer."

"Ice Age: Dawn of the Dinosaurs" held steady at No. 2 with $28.5 million, taking the 12-day haul for 20th Century Fox's prehistoric cartoon to $120.6 million. The film was the top draw internationally over the weekend, with $98 million from 102 markets. Its total foreign haul stands at $327 million.

Last weekend's North American champion, "Transformers: Revenge of the Fallen," slipped to No. 3 with $24.2 million. After 19 days, Paramount Pictures' robot sequel has earned $339.2 million in North America, easily the biggest movie of the year. Its international haul rose to $364.5 million.

The one other new entry was Fox's teen romantic comedy "I Love You, Beth Cooper," starring Hayden Panettiere in the title role. It came in at No. 7 with $5 million, in line with the studio's modest expectations.

The opening for "Bruno" was also in line with the forecasts of Universal Pictures, a General Electric Co (GE.N) unit, which paid independent producer Media Rights Capital $42.5 million for distribution rights in North America and eight foreign territories. Media Rights declined to disclose the budget.

Baron Cohen's previous release, the similarly outrageous "Borat," opened with $26.5 million in November 2006. But that was from about 800 theaters, while "Bruno" played in 2,756 theaters. "Borat" ended up with $128.5 million in North America and an additional $133 million internationally.

Universal said "Bruno" earned $20 million from the eight international markets, led by No. 1 bows in Britain ($8.1 million) and Australia ($6.1 million).

"Bruno" faced a similar storm of controversy as "Borat."

In the new film, Baron Cohen's character sashays across the American landscape, piling on the homosexual activity for unsuspecting co-stars and a squeamish audience. Critics mostly liked the movie, while gay-rights groups were mixed in their reactions.

Both films were directed by Larry Charles, a former writer/producer on "Seinfeld."