Christian Bale, star of the latest Batman blockbuster, has been released on bail by British police after being questioned on allegations of assault, media reported.

The reports could not be independently confirmed by his US representatives, who did not immediately reply to messages. But when asked if Mr Bale had been arrested and released on bail, a police spokesman said:

"A 34-year-old man has been bailed to return to a police station on a date in September."

The wording is the usual tangential way that British police have of confirming news about well-known personalities. The arrest follows an allegation of assault made by his mother and sister, British tabloid Sun newspaper said.

It came the day after Mr Bale attended the European premiere of The Dark Knight, the latest in the Batman franchise also starring the late Heath Ledger as the Joker.

Mr Ledger died of a drugs overdose shortly after completing the filming of Dark Knight, which took record box office receipts on its opening weekend in the US.

Its tally of around $155 million worth of tickets during its first three days across the US and Canada eclipsed the previous record of just over $151 million for Spider-Man 3 set in May, last year.

The studio behind the film, Warner Bros Pictures, which is part of Time Warner Inc., was not immediately available for comment.

Mr Bale was on the red carpet with co-stars Michael Caine and Maggie Gyllenhaal in central London's Leicester Square on Monday night.

A martial arts enthusiast and environmental campaigner, Mr Bale has also appeared in Batman Begins, American Psycho and Empire of the Sun.