Late actor Heath Ledger was reportedly urged to seek psychiatric help during the filming of new Batman movie The Dark Knight.

The Brokeback Mountain star played the caped crusader’s nemesis The Joker in the film, which wrapped at the end of 2007 - just weeks before Ledger was found dead from a drugs overdose in his New York apartment in January.

And the tragic star reportedly became so involved with the character he was playing, it affected his mood, sleeping patterns and relationships with other cast members.

Fox News reports that Ledger was warned not to let the movie take over his life and was pressed to seek counselling.

A source tells the broadcaster, "Heath refused to talk to anyone out of character. If you tried to communicate with him normally instead of The Joker, he would just ignore you.

"He would often come to the set to hang out even on his days off, freaking everyone out. Towards the end of filming, he was warned by people that he had gone too far, but it was almost like he couldn’t connect with those who cared for him anymore."