In March Angelina Jolie (r) adopted a child from Vietnam

Recent news reports said a woman who claimed to be the birth mother of Zahara, two, wanted the child back.

But Dr Tsegaye Berhe, head of the Wide Horizons for Children agency, told the Reuters news agency it was "media hype by unethical journalists".

At the time of the adoption, Zahara's grandmother sent a letter to the court which said child's mother was dead.

Adoptive family

"The court in Addis Ababa approved the adoption after studying the document her grandmother wrote," said Dr Berhe.

"The grandmother brought three witnesses to court who testified that Zahara's mother had died and that her father was unknown.

"The court also investigated the social status of Angelina Jolie and Brad Pitt before approving the adoption," he added.

Dr Berhe said the adoption was "legal and irrevocable".

In 2002, Jolie adopted her first child, Maddox, from Cambodia and three years later Zahara was introduced to the family.

Jolie's partner Brad Pitt later applied to become their adoptive father.

Last year the couple celebrated the birth of their first biological daughter, Shiloh Nouvel, in Namibia, Africa.

In March, Jolie adopted a three-year-old boy from Vietnam, Pax Thien Jolie-Pitt.