Scorsese's latest film, The Departed, topped the US box office

His latest movie, The Departed, cost $90m (£48.5m) and topped the US box office, but Scorsese says he is finding it harder to make films in Hollywood.

"When there are very big budgets there is less risk that can be taken," he said at the Rome Film Festival.

The director said his next project would be a "small-scale" adaptation of Japanese novel The Silence.

Written by Shusaku Endo, the book tells the story of two 17th century Portuguese missionaries.

"I have wanted to do it for 15 years," Scorsese told reporters.

Career high

The Departed is a remake of the Hong Kong drama Infernal Affairs, and stars Jack Nicholson, Leonardo DiCaprio and Matt Damon.

Nicholson plays a crime boss in Boston who plants a mole inside the city's police force, just as his own organisation is being infiltrated by an outsider.

The film gave Scorsese the strongest opening weekend of his career, taking $27m (£14.4m) at the US box office.

The director said film studio Warner Brothers had been supportive during the shooting of "an experimental film like The Departed, which we only finished three weeks ago".

"But I don't know how much longer that can hold out, with regard to what kind of movie they - the major studios - would like to make and the kind of film I'd like to make".