HONG KONG -- Jackie Chan and Jet Li say they had so much fun making their first movie together they are planning a second one.

Kung fu cinema's two biggest stars expressed admiration for each other at a Hong Kong news conference Tuesday to promote their first collaboration, the US$75 million Hollywood production, "The Forbidden Kingdom."

"The first day we started filming, it felt like we had worked together for many years," Chan said, adding, "after filming this movie, we didn't have enough fun."

"In four months (of filming), we went from friends to becoming brothers," Li said.

Chan said their fight sequences went so smoothly that cinematographer Peter Pau told them to slow down.

Chan and Li said they want to shoot another movie together based on a script they started working on 15 years ago, but both stars refused to give details.

Chan said "The Forbidden Kingdom" is not the movie he wanted to make his first collaboration with Li, but he signed on when the project came along because "if I had kept waiting, who knows how long I would have had to wait."

Both actors were lukewarm in earlier comments about the English-language movie, which was shot in China but largely targets US audiences.

"The Forbidden Kingdom" follows an American teenager's fantasy journey to ancient China, where he meets several characters from Chinese mythology such as the Drunken Immortal, played by Chan, and the Silent Monk, played by Li.

Chan and Li's friendship dates back to the 1980s. Li, a former national kung fu champion in China, said Chan watched him perform martial arts in the US then, and Chan said he played host when Li first arrived in Hong Kong to try to break into the local film industry.

Chan, the older of the two at age 53, said the two stars seldom talk about kung fu in private. He said Li, 44, a devout Buddhist, often explains Buddhist scripture to him, leaving him "very confused."

Director Rob Minkoff said bringing Chan and Li together was a difficult challenge that involved hiring a top-notch supporting crew, including famed kung fu choreographer Yuen Woo-ping, known for his work on "The Matrix" trilogy.

Cinematographer Pau won an Oscar for his work on the martial arts hit "Crouching Tiger, Hidden Dragon."

"To get Jackie and Jet together ... it's a very complicated, difficult thing," he said.

"The Forbidden Kingdom" will be released in the US on April 18 and in Asia on April 24.