The Japanese director of the acclaimed World War II prison camp drama "Merry Christmas Mr Lawrence", Nagisa Oshima, died Tuesday, his son said. He was 80.

Oshima, who had a critical hit with the controversial erotic work "In the Realm of the Senses" which famously contained unsimulated sex scenes, had been ill for some time.

"My father died calmly," Oshima's younger son Arata told AFP.

"He was with members of his family, wife Akiko and elder son Takeshi. I wasn't there. My father had been in hospital since late last year and died of pneumonia."

The younger Oshima was speaking from his late father's home in Fujisawa near Kamakura, outside Tokyo.

Oshima's cinematic career began in earnest in the 1960s with a series of films with political themes, establishing his reputation as a serious director.

Many of his works tackle issues surrounding discrimination or exploring the boundaries of social acceptability.

It was into this latter category that "In the Realm of the Senses" fell in 1976. The sexually explicit portrayal of an affair between a prostitute-turned-hotel worker and her boss was based on a true story.

The couple's relationship evolves to include elements of sadism and masochism, and ends with the protagonist dead and his genitals severed.

Further worldwide acclaim came with the 1983 film "Merry Christmas Mr Lawrence", starring David Bowie, "Beat" Takeshi Kitano and Tom Conti.

The movie, based on the writing of Laurens van der Post about his WWII experiences, depicts the shifting relationships of men in a Japanese prisoner of war camp.

Japanese musician Ryuichi Sakamoto wrote the acclaimed score for the film, in which he also starred.