COPENHAGEN (Reuters) - Denmark passed legislation on Tuesday banning bestiality, toughening a law that animal rights activists feared was encouraging animal sex tourists to visit the country.

The bill amends a previous ban on intercourse that harms animals, something Farm Minister Dan Jorgensen argued was difficult to prove.

"The current legislation does not protect the animals enough. It's hard to prove that an animal suffers when a human has sexual intercourse with it, and that is why we must give the animal the benefit of the doubt," he wrote in an opinion piece.

Those voting for the bill said Denmark did not want to remain the last northern European country where bestiality was legal, as this was attracting animal sex tourists. Germany, Norway, Sweden and Britain previously banned it.

"There are frequent reports of the occurrence of organized animal sex shows, clubs and animal brothels in Denmark," the

Danish Ethical Council for Animals, an independent advisory board under the food and agriculture ministry, said in a report, while adding that it had not been able to verify the reports.

A 2011 Justice Ministry report surveyed veterinarians and found 17 percent of them suspected that an animal they treated had had intercourse with a human.

Animal rights campaigners including PETA (People for the Ethical Treatment of Animals) petitioned Prime Minister Helle Thorning-Schmidt and Jorgensen to amend the legislation.

(Reporting By Alexander Tange; Editing by Sabina Zawadzki and Mark Heinrich)