BRUSSELS — Belgium's former king Albert II admitted on Monday he is the father of a daughter born from an affair half a century ago after a DNA test he was forced to take came back positive.

Recognizing he is the "biological father" of Belgian artist Delphine Boel, the 85-year-old ex-monarch said in a statement he had decided to halt a "painful" paternity legal battle that has dragged on since 2013, the year he abdicated and lost his immunity.

Albert had repeatedly denied being the father of Boel, who had made her claim over the past two decades before turning to the courts.

The former king agreed in May last year to take a DNA test to resolve the matter after a Brussels court levied a fine of 5,000 euros ($5,500) for each day he refused.

Boel, now aged 51, has maintained that her aristocratic mother, Sybille de Selys Longchamps, had an affair with Albert between 1966 and 1984. She was raised by her mother's husband, Jacques Boel, but won a court decision that he was not her "legal father".

Albert took over the throne following the death of his older brother, king Baudouin, in 1993. He reigned for 20 years, until 2013.

While Albert acknowledged marital problems with his wife queen Paola in the 1970s, he never admitted to having an extramarital child. He has three children with Paola, including Belgium's current king, Philippe.

In a statement on Monday, Albert's lawyers said the ex-king "has learned the results of the DNA test... (and) the scientific conclusions indicate that he is the biological father of Mrs Delphine Boel."

Albert had decided, they said, "to put an end, with honour and dignity, to this painful procedure" being heard by Belgium's appeals court over his paternity.

The lawyers argued that "legal paternity is not necessarily the reflection of a biological paternity" and noted that Albert made no "familial, social or educative decision" in Boel's upbringing.

But Boel's lawyer Marc Uyttendaele, asked on RTL television about his client's rights to a royal inheritance, said that she is "a legitimate child just like any other".

He said the admission by the former king was a "relief" for Boel "because her life has been a long nightmare because of this quest for identity".

"She had a biological father who brutally rejected her when this paternity publicly emerged," and she launched her legal fight "to avoid her children carrying this weight," Uyttendaele said.

The lawyer said the statement from Albert "is characterized by a lack of elegance, a lack of humanity... the statement continues to confirm this lack of love". — AFP