Horrified tourists watched as a pride of lions ate a zookeeper alive in Thailand this morning.

The beasts pounced on the worker when he stepped out of his jeep to pick rubbish up from the floor in the open enclosure at Safari World in Bangkok at around 11 am local time.

Shocked visitors screamed as the predators pinned down their victim.

Onlookers, including a number of zoo workers, could only sound their horns in a futile attempt to scare away the sub-Saharan big cats as they feasted on human flesh.

Officials arrived with guns, which caused the lions to scatter, but the zookeeper Jian Rangkasamee was already mauled to death as the lions gnawed his body until the bones were exposed.

Zoo staff eventually drove the lions away and closed the drive-through area, where a puddle of blood could be seen on the ground.

Eye-witness Professor Tavatchai Kanchanarin, a doctor at a leading hospital who was visiting at the time, said: 'The lion attacked the zookeeper while he was getting out of his car. It was about 10 metres away, then slowly approached and grabbed the zookeeper from behind, dragging him to the ground and biting him.

'Three or four other lions then joined in with biting the zookeeper.

'Many people witnessed the incident but didn't know how to help. They honked their own car horns and shouted for help.

'At first, I assumed it was familiar to the zookeepers, as the person who was bitten might have been a lion keeper. I thought the lions were trying to hug him, so no one went near that area.'

The professor said the attack continued for around 15 minutes before zoo staff were able to reach the victim. He was rushed to the hospital but was pronounced dead upon arrival.

Owners at the Bangkok World Safari Park have yet to comment on the incident. Local media reported that the attack happened outside of feeding hours for the lions.

The victim, Jian, was reportedly an experience conservationist who had worked at the safari park since April 2019.

A spokesman for the government's Department of National Parks, which is responsible for zoos, said staff were on their way to the facility to check on the animals and the safety measures in place.

The park is best known for its orangutan that hugs and gropes female visitors as they pose for pictures.

However, the attraction has attracted criticism from animal rights groups such as PETA, who claim the ape is subject to poor treatment while being 'humiliated and exploited'.