Michelle Williams and Naomi Watts have publicly paid tribute to the late Heath Ledger for the first time since the actor's tragic death.

The 28-year-old was found dead in his New York apartment on January 22nd after an accidental overdose of prescription medication.

And his former partner Williams - the mother of his daughter Matilda - has told Interview magazine of his "uncontrollable energy".

His co-star in 2005's Brokeback Mountain - for which he received a best actor Oscar nomination - Williams said: "He buzzed. He would jump out of bed. For as long as I'd known him, he had bouts with insomnia.

"He just had too much energy. His mind was turning, turning, turning - always turning.

"He had a talent for everything that he put his mind to. He didn't know limits."

The Dawson's Creek actress explained that the most interesting thing about Ledger was "how vulnerable he was".

"You can pick up on it in his performances, but it's easy to overlook because he was so physical and beautiful and strong and masculine," she explained.

"But there was always that underlying sensitivity. That's who he was."

Eastern Promises star Watts, who was in a relationship with Ledger for two years, described his acting as "just so touching, so connected in truth".

"I think he was just getting started," she added.

A statement released by the New York City medical examiner's office said the drugs that killed Ledger included sleeping pills, painkilling medication and anti-anxiety tablets.

Ledger's turn as The Joker in the upcoming Batman sequel The Dark Knight can be seen in the UK in July.

13/03/2008 12:39:22