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BRUSSELS (Reuters) - The Brussels appeals court has ordered the retired king of Belgium to take a DNA paternity test, overturning an earlier ruling in a suit brought by 50-year-old artist Delphine Boel.

Under the judgment, reported by Boel’s lawyers on Monday, King Albert II must take the test within three months or risk being presumed to be her father -- although his lawyers could seek to challenge the court’s legal argument.

The 84-year-old monarch, who in 2013 abdicated in favor of his son Philippe after 20 years on the throne, has contested Boel’s claim for more than a decade. Court-ordered DNA tests have proved that she is not the daughter of Jacques Boel, scion of one of Belgium’s richest industrial dynasties.

The court could not be reached, and there was no immediate comment from the royal house. Boel’s lawyers said in their statement that they were pleased with the “strong affirmation of the principle of acting in the interests of the child” as she seeks legal confirmation of her true identity.

That identity became a topic of public debate after the publication in 1999 of a biography of Queen Paola, Albert’s Italian wife, which alleged that he had had a long extra-marital relationship from which a daughter was born in the 1960s.

Albert, who has no formal public role, has acknowledged that he and Paola had marital difficulties. Their three children are all older than Boel. Next in line to the throne is 17-year-old Princess Elisabeth, daughter of Philippe and Queen Mathilde.