A man who was believed to be dead shocked emergency responders when he suddenly woke up while they were retrieving his body.

Kosem Wanaeloh, 70, was lying motionless with visible wounds and blood on his face as he floated in the channel in Nonthaburi, Thailand, on June 11.

Rescue workers were called to the scene on the outskirts of Bangkok after a local fisherman spotted Kosem in the water while fishing from a nearby bridge shortly after midnight.

Officers arrived and found the man propped against a concrete block, with what appeared to be a fertiliser sack resting on his body.

Believing he had drowned, they set to work to recover the body. But as one officer used a stick to shift the block, the presumed corpse suddenly stirred awake and shouted: 'Help me!'.

The shocked personnel immediately dragged Kosem out of the canal, where he was believed to have been lying for at least four hours. They rushed him to the Bang Bua Thong Hospital for treatment.

Speaking today from his hospital bed, Kosem said: 'Yesterday, I walked out of the Bang Bua Thong Market and kept walking all day. When it got dark, everything started to look the same, and I couldn't find my way back.

'I thought I was walking toward a school, but I was lost. I was exhausted, dizzy, and suddenly fell into the water. I must have hurt my face when I hit a rock while fainting.'

The villager, who used to work as a labourer, said he stayed still, fearing a crocodile was in the canal. He then reportedly fell asleep while playing dead.

Kosem's son Anusorn, 40, was teary-eyed after seeing his father safe. He said he lived separately from his father, but often visited him because he was sick.

He said: 'Yesterday, I went to give him some food, but he was missing from the market. I looked all day for him, but it was only after I watched the news that I learned he had fallen into the canal.'

Anusorn said Kosem lived at the market after falling on hard times due to the economic downturn. He added he and his younger brother had decided to care for their aging father, who had been living apart from his family.