A South African animal welfare activist claims he was brutally assaulted and threatened with death while filming alleged abuse of donkeys on the Greek island of Santorini.

Luke Barritt, a campaigner for international charity Network for Animals (NFA), said he was spotted filming mistreatment and abuse of donkeys by their owners and, together with cameraman Wiktor Dobraczynski, was "attacked" by a group of 10 people.

Barrit and Dobraczynski had been documenting the treatment of donkeys, after a promise made by the Greek government in 2018 to improve conditions.

According to Barritt, who has since returned to Cape Town from Greece, he was kicked, struck and threatened that he'd be thrown off a cliff by the donkey owners.

"The sheer venom of the donkey owners stunned me. They were kicking me and beating me with the same whips they use on the donkeys. It was a truly frightening experience," Barritt said.

Some of the mistreatment Barritt said he witnessed included owners making their donkeys climb a 300m cliff in the scorching sun, with no food, shade or water.

"I escaped, but the worst thing is that there's no escape for the donkeys. They are forced to climb that cliff from sunrise to sundown. They are not given food or water, so as to not soil the cliff path. The cruelty is horrifying."

Barritt said he had reported the matter to Greek police, who had promised to take action, but nothing had come of it.

He said it was clear that the promised improvements had not been made, labelling it a "disgrace" and urging visitors to be aware of the cruelty.

The Department of International Relations and Cooperation (Dirco) said it had not received any report on the alleged attack.

Dirco spokesperson Clayson Monyela said the department received weekly reports from the consulate and there was currently no report on Barritt's attack.