It Was Just An Accident by Irans Jafar Panahi wins Cannes top prize

*

Panahi last in person at Cannes festival in 2003

*

Grand Prix awarded to Joachim Trier's "Sentimental Value"

*

Brazil's "Secret Agent" wins best actor, director awards

(Adds details in paragraphs 6, 8-12, 14)

By Miranda Murray

CANNES, France, May 24 (Reuters) - Revenge thriller "It Was Just An Accident" by Iranian director Jafar Panahi, who was last at the Cannes Film Festival in person more than 20 years ago, won the Palme d'Or top prize on Saturday.

Panahi, who has been arrested several times for his filmmaking and was under a travel ban until recently, last attended the festival in person in 2003, when "Crimson Gold" was screened in the Un Certain Regard category.

"Art mobilizes the creative energy of the most precious, most alive part of us. A force that transforms darkness into forgiveness, hope and new life," said jury president Juliette Binoche when announcing the award.

"It Was Just An Accident" follows Vahid, played by Vahid Mobasseri, who kidnaps a man with a false leg who looks just like the one who tortured him in prison and ruined his life.

Vahid sets out to verify with other prison survivors that it is indeed their torturer - and then decide what to do with him.

An emotional Panahi, wearing sunglasses on stage, thanked his cast and film crew during his acceptance speech.

The Grand Prix, the second-highest prize after the Palme d'Or, was awarded to "Sentimental Value" from acclaimed director Joachim Trier.

The jury prize was split between the intergenerational family drama "Sound of Falling" from German director Mascha Schilinski and "Sirat", about a father and son who head into the Moroccan desert, by French-Spanish director Oliver Laxe.

Brazil's "The Secret Agent" won two awards, one for best actor for Wagner Moura, as well as best director for Kleber Mendonca Filho.

"I was having Champagne," said Mendonca Filho after he ran up to the stage to collect his award after celebrating Moura, who previously made a name for himself in hit TV series "Narcos".

Newcomer Nadia Melliti took home best actress for "The Little Sister", a queer coming-of-age story centred around the daughter of Algerian immigrants in Paris.

Belgium's Dardenne brothers, who have the rare honour of already having won two Palme d'Or prizes, took home the award for best screenplay for their film "Young Mothers".

Twenty-two films in total were competing for the prize at the 78th Cannes Film Festival, with entries from well-known directors Richard Linklater, Wes Anderson and Ari Aster.

Saturday's closing ceremony officially ends the glamour-filled festival that began on May 13. (Reporting by Miranda Murray; Editing by Jan Harvey)