Paul Watson, a Canadian environmentalist and star of a reality television show, says Canada has effectively barred him from returning to the country since his passport was seized three years ago by German authorities.

Watson, founder of the Sea Shepherd Conservation Society whose boats have been involved in high seas confrontations, said he believes the decision was driven by Canadian Prime Minister Stephen Harper’s dislike of environmentalists. He said it was unlikely that a low-level bureaucrat would have unilaterally decided to confiscate his passport.

Watson initially made the claim in a Facebook posting on June 6.

The Canadian Citizenship and Immigration Department said it was not immediately able to answer questions about the case.

Watson, 64, who holds both U.S. and Canadian citizenship, had both passports seized by German authorities in 2012 after they detained him on warrants from Japan and Costa Rica.

German authorities later gave the passports to local U.S. and Canadian missions in Germany. But while the Americans returned his passport, he said the Canadian consulate in Frankfurt held onto his Canadian passport and officials declined to explain why they could not return it.

“They’re just basically stonewalling me on this,” Watson said in a telephone interview with Reuters. Watson said he was in Paris and has been there since July 2014.

Watson, whose organization is featured on the reality television show “Whale Wars,” said he has not been able to return to Canada because he is required to show his Canadian passport to return to the country. He said he has not attempted to return to Canada because he believes he would be turned away at the border.

“I have a lot of family in Canada right across the country,” Watson said. “I just find it incredible that as a Canadian citizen, I can’t return to my own country - the country I was born in - without any explanation given to me as to why.”

On his Facebook page, Watson, an early member of Greenpeace, accused Harper of being personally responsible for taking his passport. But when asked about this claim, Watson said he did not have direct evidence.

The Sea Shepherd group has had a series of legal battles in recent years. It announced a $2.55 million settlement on June 8 with Japanese whalers who accused it of violating a court injunction requiring Sea Shepherd vessels to stay away from the Japanese vessels.

A few years earlier, Canadian officials had seized another Sea Shepherd ship documenting the seal hunt in March 2008 following a confrontation with a Canadian Coast guard vessel. Both sides accused each other of causing a collision, and two Sea Shepherd crew members were later fined.