Graham George Spencer said he was bitten “26 times in 10 seconds” by the otters during the attack, as he was out walking with a friend one morning in the city state’s Botanic Gardens.
“I actually thought I was going to die – they were going to kill me,” the British man told The Straits Times.
He was bitten in the ankles, legs and buttocks. Some of his wounds were deep enough to require stitches.
Since the attack he says he has had difficulty sleeping and sitting down as there were 18 “puncture bites” on his buttocks, he told the Today local website.
Mr Spencer, a British citizen living in Singapore and owner of a maid agency, said the attack happened at the end of his walk on 30 November.
He initially spotted 20 otters crossing a pathway near the gate. The group was crossing calmly but “went crazy” when a jogger ran towards them.
The otters tried to bite the runner but he escaped. The animals then may have mistaken Mr Spencer for the runner and attacked him instead. He said the otters suddenly went “crazy like dogs”.
“All of a sudden, they must have thought I was [the runner],” he said. The otters jumped on Mr Spencer, who is in his sixties, and began biting, causing him to fall on his face.
His friend, who was walking a little ahead of him, screamed and shouted at the animals to get them off. The screaming only stopped them momentarily.
“I was bitten 26 times in 10 seconds. If it wasn’t for my friend, I don’t think I’d still be here. I’d be dead,” Mr Spencer said.
The frightened duo managed to escape and run towards a nearby visitors centre but the otters chased them briefly.
The staff at the visitors centre gave Mr Spencer a tetanus shot and oral antibiotics. However, he had to go to a hospital three times since then, costing him more than £900.
A representative of the Botanic Gardens promised Mr Spencer that an investigation was under way. But he has sought stringent measures in the park to prevent such attacks in future. “You got to keep the public away from [the otters] because this will happen again,” he said.
The incident has led some there to call for a cull of the local otter population.
Otters are generally docile. Authorities say such attacks are rare but advised people to stay away from the animals.
A collective noun for otters is romp, because they are usually seen as playful animals.
But it is not the first time there have been reports of otters attacking.
In October, concern was raised over a group of “violent” river otters in Alaska which attacked humans and other animals.