Batman star Christian Bale has asked for privacy in his fist comments since allegations he assaulted his mother and sister at a London hotel, saying the incident was personal.

The Welsh-born actor brushed off questions about the alleged family dispute, saying he preferred to focus on the blockbuster movie The Dark Knight, which has just opened in Spain.

"It's a deeply personal matter," Bale told a news conference at a luxury hotel in Barcelona. "I would ask you to respect my privacy in the matter."

Bale, 34, spent four hours talking to British police on Tuesday following allegations he assaulted his mother and one of his three sisters in his suite at London's Dorchester Hotel two days earlier. He was released on bail, but not charged.

Bale has said through his lawyers the assault allegations were false.

British media reported that Bale's mother and sister told police he assaulted them at the hotel a day before attending the European premiere of The Dark Knight. The Sun newspaper said the complaint was filed by sister Sharon Bale and mother Jenny Bale.

The drama unfolded even as the movie broke records and was met with critical acclaim.

The film, which stars Bale as Batman and the late Heath Ledger as the superhero's nemesis The Joker, opened in Barcelona at a glittering premiere. Thousands of fans lined the red carpet for a peek at the stars.

The movie is expected to do well in Spain thanks in part to the publicity which Bale's reported arrest and Ledger's untimely death had spawned, media reports said.

Bale first made a splash as the child star of Steven Spielberg's Empire of the Sun in 1987. His screen credits also include American Psycho, The Machinist and Batman Begins.