By Crispian Balmer and Mike Davidson

VENICE The make-up artist for Bradley Cooper's Leonard Bernstein biopic "Maestro" apologised on Saturday for offending people by giving the lead character a prosthetic nose, but said he only wanted authenticity.

Bernstein, the son of Jewish immigrants to the United States, was a celebrated U.S. conductor and composer, who wrote classical musical and hit musicals like "West Side Story".

Cooper directed, produced co-wrote and stars in "Maestro", which received its premiere in Venice on Saturday.

When the first trailer of the film surfaced last month, some critics complained that the nose pandered to Jewish stereotypes.

Bernstein died in 1990 but his adult children have defended the make-up in the film, saying their father had had a "nice, big nose".

Cooper is not in Venice to present his Netflix production because of a Hollywood actors' strike that prevents promotional work. But his make-up designer Kazu Hiro met the press and said he was surprised by the nose criticism.

"I feel sorry that I hurt some people's feelings. My goal was, Bradley's goal was to portray Lenny as authentically as possible, and Lenny had an iconic look that everyone knows. There are so many pictures out there," he said.

"We wanted to respect and love that look," he said.

Hiro said it took two hours to fix the nose onto Cooper when he was portraying the younger Bernstein, but up to five hours as the character reached old age.

Bernstein's daughter, Jamie, said that Cooper had involved the family closely in the development of the film, which focuses on the composer's relationship with his wife, played by British actor Carey Mulligan, and his bisexuality.

"He chose to tell this very intimate story about our parents and to really include my brother, sister and me in his process. And really, we didn't expect that," Jamie Bernstein said.

"We never dreamed that he would go to the lengths that he did to include us in his process and to go to these incredible lengths to maintain authenticity," she added.

"Maestro" will play on Netflix from Dec. 20. It is one of 23 movies competing for the Golden Lion award at the Venice Film Festival, which runs until Sept. 9.

(Reporting by Mike Davidson and Crispian Balmer, Editing by Angus MacSwan)