A group of tourists were left ‘distressed’ as two grizzly bears brutally battled over mating rights mere metres away from their boat.

Vanessa Obran and her husband John were on a tour of a bay in British Columbia, Canada, when they spotted two bears mating on the shore.

Dramatic footage captured the moment a jealous male sprinted across the shale and tackled one of the mating pair and pinned it to the ground.

In an epic 17 minute encounter, the two testosterone-fuelled bears tore chunks of flesh off each other with their teeth and paws, and even took their fight into the water.

Vanessa, from Australia, said: “While filming, the violence made me feel physically sick to the stomach.

“I love bears so much and the violence was so hard to watch. There are parts of the video that I don’t watch now as it is distressing.

“One minute we were watching a tranquil scene of two bears mating on the beach. We thought how lovely, that is something you don’t see very often. Then all hell broke loose.

“They were fighting over mating rights. Both bears had a lot of injuries, cuts and bites. They were about 8ft tall on their hind legs.

“I had filmed a bear fight before in Alaska but it was only a few swipes. Nothing as brutal as this.

“Having said that, I knew what a rare occurrence this was to witness and I feel so lucky to have been there at the right time and right place.

“To see them fight for so long is nearly unheard of. Wildlife guides we have since spoken to, who have been watching bears for 30 years, have never seen anything like it.

"We made our first trip to Yellowstone National Park in 2012 where we saw our first wild grizzly bear. We were hooked.

“Since then we go to the US and Canada every two years and spend up to three months going to the National Parks to see bears, moose, wolves. Any animal at all we are happy to spot.

“It becomes an addiction. It is so thrilling to spot an animal in the wild.”