A German court on Friday granted bail to Paul Watson, the founder of marine conservation group Sea Shepherd, while authorities decide whether he can be extradited to Costa Rica.

The higher regional court in Frankfurt said in a statement a Costa Rican extradition request would be considered on charges stemming from a high-seas confrontation over shark finning in 2002.

Watson, a Canadian national whom Sea Shepherd members affectionately call "the captain" -- and who looks the part with a thick shock of white hair and beard -- is accused of "putting a ship's crew in danger".

According to Sea Shepherd, the incident took place in Guatemalan waters when the organisation encountered an illegal shark finning operation run by a Costa Rican ship called the Varadero.

Sea Shepherd says that while escorting the Varadero back to port, a Guatemalan gunboat was dispatched to intercept the Sea Shepherd members after the crew of the Varadero falsely accused the Sea Shepherds of trying to kill them.

The court said the alleged crimes would also have been against the law in Germany and had not passed the statute of limitations, and therefore ordered Watson to be placed in custody awaiting an extradition decision.

This decision can only be taken by the German justice ministry after several more legal steps, Ingo Noehre, a court spokesman, told AFP.

At the same time, the court ruled that Watson should be released on bail of 250,000 euros ($318,000).

"He may however not leave Germany while the extradition process is being decided and must adhere to further conditions," the court said in a statement.

The veteran environmentalist was detained in Frankfurt on Sunday.

Sea Shepherd is best known for its annual pursuit of the Japanese whaling fleet in Antarctica, using increasingly militant ways to halt the hunt.

Watson has said that his organisation was the only navy in the world that defends the oceans. "Our goal is to protect the oceans because if they die, we will all die," he told AFP in a 2010 interview.