Ms Cohen-Ahnine wrote a book describing her fight to "get back" her 11-year-old daughter, Aya, who the mother claimed has been held captive by the girl's father, Prince Sattam al-Saud from the Saudi royal family, since September 2008.

"She was a woman who was a real fighter and a very positive person, and plus, there were plans to see [her daughter] Aya in mid-September. That was her greatest motivation of all."

"What I can tell you is that it wasn't a suicide," Ms Tarquiny-Charpentier said.

Ms Cohen-Ahnine's lawyer, Laurence Tarquiny-Charpentier, said the death "seemed to be some sort of accident", and did not know whether foul play was involved. She said there were witnesses, and more information is expected today.

She alleged that when she agreed to visit Prince Sattam with her daughter in 2008, she was locked up in a Riyadh palace, and accused by authorities of being a Muslim who converted to Judaism, a crime punishable by death in Saudi Arabia. When a maid left her door open she was able to escape to the French embassy, and return alone to France.

In January a Paris court ordered Prince Sattam al-Saud to hand over custody of his daughter to her mother and provide child support of euros 10,000 ($11,825) a month. But the prince reportedly dismissed the ruling, and said: "If need be, I'll go like [Osama] bin Laden and hide in the mountains with Aya."

Ms Cohen-Ahnine's lawyer said negotiations with the prince had led to improved ties, and a planned visit with Aya was due next month. He said simply organising the visit was an achievement. "We spoke on the telephone the day before she died. We were supposed to meet tomorrow to get things ready," said Ms Tarquiny-Charpentier. "It's so painful, and at the same time, there is a feeling of failure."

Ms Cohen-Ahnin met the prince in London and their daughter was born in November 2001.

Their relationship continued until 2006 when he allegedly announced he was obliged to marry a cousin, but that she could be a second wife. She refused and they separated.