French President Emmanuel Macron's office said Tuesday he was pressing Danish authorities not to extradite arrested anti-whaling activist Paul Watson to Japan.
Watson, the 73-year-old American-Canadian founder of activist group Sea Shepherd, has lived in France for the past year.
Macron is "following the situation closely" and "intervening with the Danish authorities," his Elysee palace office said.
Watson was arrested in Greenland, an autonomous Danish territory, on Sunday under an international arrest warrant issued by Japan.
He is to remain in custody until Aug. 15, while the Danish justice ministry must decide on whether he should be extradited.
In France, an online petition for Macron to call for Watson's release has gathered 388,000 signatures.
Green party lawmakers also pressured Macron, while 89-year-old film legend Brigitte Bardot told Le Parisien daily Monday: "We must do everything to save Paul."
Watson's ship docked in Greenland's capital Nuuk Sunday to refuel and he was arrested on board.
The vessel was on its way to "intercept" a Japanese whale hunting and processing ship in the North Pacific, his Captain Paul Watson Foundation said in a statement.
Japan is one of the last three countries in the world to permit commercial whaling along with Iceland and Norway.
Watson's foundation said he was the target of an Interpol red notice over events during a clash with a Japanese whaler in the Antarctic dating back to 2010, including property damage and injuries.
"The Japanese arrest warrant is illegal. It violates all international human rights treaties," said Francois Zimeray, one of Watson's lawyers.