Screen legend and animal rights campaigner Brigitte Bardot on Tuesday offered to take marine conservation activist Paul Watson's place in prison, saying she was "outraged" by his arrest in Germany.

"Being outraged by the fact that he's been put in prison, I offer to take his place because I am his accomplice," Bardot, 77, said in a statement after the founder of marine conservation group Sea Shepherd was detained.

"I have always supported Paul Watson, my brother in arms," said the retired French actress who had a Sea Shepherd trimaran named after her in 2011.

A German court on Monday ordered Watson, 61, to remain in custody a day after his arrest on a warrant from Costa Rica where he is accused of endangering a shark-finning ship's crew during a 2002 confrontation.

Watson was passing through Frankfurt with French European Parliament members Daniel Cohn-Bendit and Jose Bove on his way to France to attend conferences when he was arrested.

Bardot has over the years campaigned against whaling in Japan, bear-hunting in New Jersey, wolf-hunting in Sweden, dolphin slaughter in Denmark and other animal rights causes.

She is married -- for the fourth time -- to a former aide of the founder of France's far-right anti-immigrant National Front, Jean-Marie Le Pen.

She has been fined for inciting hatred against Muslims by attacking the "Islamisation" of France and the ritual slaughter of animals in Islamic culture.