Siblings of actress Yun Jung-hee, known to be long suffering from Alzheimer's disease in France, have requested guardianship for their older sister at a South Korean court, according to sources.

Yun, 76, is best known outside the country for her lead role in South Korean director Lee Chang-dong's "Poetry," which won best screenplay at the Cannes Film Festival in 2010. She has been long married to renowned pianist Paik Kun-woo.

The development is the latest in a legal fight over her guardianship between her husband and daughter based in France and her siblings here. A French court earlier ruled in favor of Paik and his daughter in November.

In a decision that would pit Yun's younger siblings against her daughter, the Seoul Family Court on Monday allowed her younger brother to officially participate in a court case in which her daughter requested the guardianship of her mother in South Korea, the sources said.

With the decision, Yun's siblings -- who have claimed they should take care of her in her home country -- are now allowed to submit relevant documents and testify at the court.

"Yun's third youngest sibling is taking part in the case to represent her five younger siblings here," a source close to the younger brother told Yonhap News Agency. "(He) will submit letters to the court and explain their stance on the guardianship issue at court."

The court has been in consultation with the national mental health center to clarify Yun's health status. A medical document review usually takes place in court cases over adult guardianship.

Upon receiving feedback from the national center, the court is expected to hear from Yun's daughter and her siblings before deciding on who will get the guardianship. (Yonhap)