"Child's Pose", a mother-son psychodrama set among post-communist Romania's new ruling class, won the Golden Bear top prize at the 63rd Berlin film festival Saturday.

Director Calin Peter Netzer, a member of Romania's renowned new wave in cinema, tells the story of a wealthy and controlling mother who fights to get her son acquitted after he kills a poor teenager with his car.

"I want to thank the jury for this amazing prize, this wonderful prize," Netzer told the panel led by Chinese director Wong Kar Wai, adding later at a press conference he was "shell-shocked" by the honour.

The Berlinale, the first major European film festival of the year and typically its most politically minded, handed two prizes to the Bosnian docu-drama "An Episode in the Life of an Iron Picker".

Nazif Mujic, the real-life protagonist of the picture about a Roma couple denied life-saving medical treatment, was the surprise winner of the Silver Bear best actor prize.

The ultra-low-budget film also took the runner-up jury prize.

Its director Danis Tanovic, who won an Oscar for his 2001 wartime black comedy "No Man's Land", said his anger after reading news reports about the couple led him to seek them out.

"I'm so happy for Nazif and his family because the whole point of this film was to try and change their lives and I hope it changes their lives," he told reporters.

David Gordon Green picked up the Silver Bear best director award for his quirky US buddy picture "Prince Avalanche", a remake of the 2011 Icelandic film "Either Way".

The movie, the only comedy among the 19 contenders at the festival, stars Paul Rudd and Emile Hirsch as highway maintenance workers in Texas at crossroads in their lives.

Best actress went to Chile's Paulina Garcia for "Gloria", a feel-good movie about a middle-aged divorcee who refuses to give up on a shot at happiness.

Best screenplay went to "Closed Curtain" by Iranian dissident director Jafar Panahi and his longtime collaborator Kambuzia Partovi, a film made in secret in defiance of a ban by the authorities in Tehran.

"It is impossible to stop a thinker and a poet. Their thoughts bear fruit everywhere," Partovi said, accepting the award because Panahi was not granted permission to travel.

A debut feature from Kazakhstan, the bullying drama "Harmony Lessons", grabbed a Silver Bear for extraordinary artistic achievement for its cinematographer Aziz Zhambakiyev.

And a Canadian thriller about a lesbian couple trying to put their prison past behind them, Denis Cote's "Vic and Flo Saw a Bear", clinched a prize for "a work of particular innovation".

"Child's Pose" figured in an especially strong year for films exposing new fissures and rampant corruption in the former communist bloc.

Lead actress Luminita Gheorghiu, best known for her 2005 dark comedy "The Death of Mr Lazarescu", dazzled movie-goers as a manipulative mother who sees the fatal accident as a chance to reconnect with her estranged son.

Netzer said the story of generational conflict was "universal".

"I think basically this is about a relationship, a kind of pathological relationship between mother and son," he told reporters. "This is a kind of Oedipus complex. Clearly we are referring to Freud."

Producer Ada Solomon said the Golden Bear would give the film a much-needed boost.

"I think that Romanian politicians should pay much more attention to the ambassador that our cinema is around the world," she said, slamming subsidy cuts.

"I want to thank those people who didn't help us and didn't support us and that made us more determined."

Critics noted a stand-out year for seasoned actresses at the festival including well-received performances by Catherine Deneuve, Juliette Binoche and Garcia, who before "Gloria" was known mainly for her work in telenovelas.

"Directors seem to have discovered the value of maturity and been anxious to explore the female face and psyche as they age, gracefully or otherwise," the trade magazine Hollywood Reporter wrote.

List of winners (main prizes) at 63rd Berlin film festival:

- Golden Bear for best film: "Pozitia Copilului" (Child's Pose), Calin Peter Netzer. Romania.
- Jury Grand Prix Silver Bear: "Epizoda u zivotu beraca zeljeza" (An Episode in the Life of an Iron Picker). Bosnia/France/Slovenia.
- Silver Bear for best director: David Gordon Green for Prince Avalanche (US).
- Silver Bear for best actress: Paulina Garcia in "Gloria" (Gloria). Chile/Spain.
- Silver Bear for best actor: Nazif Mujic in "Epizoda u zivotu beraca zeljeza" (An Episode in the Life of an Iron Picker). Bosnia/France/Slovenia.
- Silver Bear for outstanding artistic contribution (camera): Aziz Zhambakiyev for "Uroki Garmonii" (Harmony Lessons). Kazakhstan/Germany.
- Silver Bear for best screenplay: Jafar Panahi for "Parde" (Closed Curtain). Iran.
Alfred Bauer Prize for work of particular innovation: "Vic+Flo ont vu un ours" (Vic+Flo Saw a Bear). Canada.
- Best first feature film: "The Rocket" by Kim Mordaunt. Australia/Laos/Thailand.
- Golden Bear for best short film: "La Fugue" (The Runaway) by Jean-Bernard Marlin. France.
- Teddy for best film with gay or lesbian context: "W imie" (In the Name of) by Malgoska Szumowska. Poland.