PARIS, Feb 5, 2010 (AFP) - Legendary US director Martin Scorsese and his favourite actor Leonardo DiCaprio said Friday they took their collaboration to new heights for the gothic thriller "Shutter Island".

The Oscar-winning director who made a star of Robert De Niro in "Taxi Driver" and "Raging Bull", has formed a close bond in the past decade with DiCaprio since "Gangs of New York".

After "The Departed", which finally gave Scorsese the Best Director Oscar, "we began to realise there was something more that we could push with each other," Scorsese told a press conference in Paris.

With "Shutter Island", their fourth collaboration, they saw an opportunity.

The film, in competition at next week's Berlin Film Festival, follows two US marshals in 1950s Massachusetts pursuing a missing psychiatric patient on Boston's remote Shutter Island.

When a hurricane hits the area, the marshals are stranded on the island, home to a hospital for the criminally insane.

In their previous films together, "you had to dig deep in the recesses of a psychiatric labyrinth," Scorsese said, and with "Shutter Island" they saw a new opportunity but, he joked, they did not realise how far it would push them.

"At its core it's a character piece," DiCaprio said. "It's one man's journey dealing with his own emotional cathartic trauma."

"Shutter Island" evokes paranoia and fear in 1954, but Scorsese said there were parallels with today. "The War is The War... The horrors of that are something we all have to deal with and constantly think about. And question."

More Scorsese-DiCaprio films seem likely to follow.

"There is an element of trust that just happens naturally over time," DiCaprio said. "We share the same taste in film... we certainly know the directions that we don't want to go in".

"Shutter Island" also stars Ben Kingsley, Mark Ruffalo and Max von Sydow.