SEOUL (AFP) - French art experts on Tuesday (Dec 27) lambasted South Korean state prosecutors for declaring a "fake" painting to be genuine despite its own scientific findings that supported the artist's disavowal of the work.

The painting Beautiful Woman by one of South Korea's most renowned artists, Chun Kyung Ja, has been the focus of a bizarre and decades-long dispute over its authenticity.

Before her death last year at the age of 91, Chun had repeatedly insisted that the 1971 portrait owned by the country's National Museum of Modern and Contemporary Art (MMCA) was not one of hers.

"Parents can recognise their children. That is not my painting," she insisted.

The museum is adamant that it is genuine, and in April a prosecutorial investigation was launched after one of Chun's daughters filed a complaint. She accused former and current MMCA officials of hurting the artist's reputation by promoting the painting as authentic.

State prosecutors last week found in favour of the museum, citing forensic evidence and the opinion of local art experts.

They also clarified the provenance of the painting, saying it was once owned by the former head of the South Korean spy agency and was appropriated by the government after he was executed for assassinating then President Park Chung-Hee in 1979.

"This announcement is an egregious affront to the justice system," French imagery analysis firm Lumiere Technology and Chun's relatives said in a joint statement.

The statement accused the prosecution of continuing to "willfully avoid seeking the truth even when presented with it".

Chun, born in 1924 in a small town in the southern part of the Korean peninsula, was best known for her paintings of female figures and flowers using vivid primary colours that broke with traditional South Korean styles.

Her works have recently sold at auction for between US$700,000 (S$1 million) and US$1 million.

Lumiere Technology said it published a 63-page report after a "thorough" and scientific examination of the piece and nine authenticated paintings by Chun.

Based on forensic analysis using specialist technology, Lumiere Technology concluded that Beautiful Woman is "absolutely and unequivocally a forgery".

But the prosecution authorities "completely disregarded" Lumiere Technology's scientific results, arriving at a conclusion based on "statements and notions backed by no evidence", it said.

"The prosecution's denial of empirical evidence is akin to a DNA paternity test - for a child revealing that a man is in fact not his father - being disregarded in place of the mother's testimony that the child must be the offspring of that man because she never had a relationship with another man," it added.

Chun's family has also rejected the prosecution's conclusion, accusing it of seeking to help the state museum authorities save face.

"We wonder if the prosecutors... caved in to political pressure," the family said.

They vowed to pursue efforts to have it declared a forgery.