South Korean actress Jeon Do-yeon poses after winning the Best Actress prize during the Closing ceremony of the 60th edition of the Cannes Film Festival at the Festival Palace in Cannes, southern France.[AFP]

South Korean actress Jeon Do-yeon, who stars in a tragic movie on death and faith, "Secret Sunshine", won the Cannes filmfest's best actress award Sunday.

The 34-year-old actress was acclaimed for her brave performance as a grieving wife and mother in the South Korean melodrama, the first picture in four years by Lee Chang-dong, a former South Korean culture minister.

"I can't believe I'm here," said Jeon, wearing a silver lame evening gown.

"There are many fabulous actresses here at the festival and I would like to represent them all here tonight. It is a great honour for me to have this prize."

She has appears in nearly every scene of Lee's two-and-a-half-hour-long film, portraying Shin-ae, a piano teacher who moves with her son to the hometown of her late husband, whose death is still the source of nearly unbearable pain.

She dotes on her young son as a link to his father and the two have a palpably close relationship.

When, in a cruel and unexpected twist in the story, the small boy is abducted and killed, Shin-ae turns to evangelical Christianity on the advice of her pharmacist, a devout believer, as a means of dealing with her grief.

Filled with religious fervour, she decides to visit her son's murderer in prison to tell him she has forgiven him.

But she is horrified when the killer tells her with a serene smile that he has repented and God has already offered him absolution.

"Who is God to forgive him before I have?" she asks her Christian friends in a rage.

Jeon is known as a chameleon of Korean cinema, who fully inhabits her roles.

She shot to stardom at home with her debut 1997 romance "The Contact".

The following year she starred as a schoolgirl in "Harmonium in My Memory" and picked up South Korea's prestigious Blue Dragon and Grand Bell prizes for best actress.

Jeon scored a box office hit in 2003 with a remake of "Dangerous Liaisons" and won rave reviews in 2005 for her portrayal of a prostitute who contracts AIDS in "You're My Sunshine."

"Secret Sunshine" was one of two South Korean moving competing for the Palme. Kim Ki-duk presented "Breath," starring Taiwanese actor Chang Chen as a man on death row who falls in love with a scorned wife.