A pensioner miraculously survived being stuck in mud for 18 hours after collapsing in the middle of a rice paddy in Thailand.

Kamchan Setthawong, 86, was found caked in mud and shivering as he lay in a field in Udon Thani province at 10 am local time on December 14 .

He had gone to the paddy to cut some grass the day before, but passed out from a stroke due to clogged arteries stifling blood flow to his brain.

His family grew worried when he failed to return home that night, with temperatures plummeting to 13 degrees Celsius.

Fearing he might have been attacked and left for dead by bandits, they called rescue services to search for the missing villager.

The search team of more than 20 people scoured the field and a nearby pond all morning. They discovered Kamchan's favourite white bike parked next to the rice paddy, but still could not pinpoint his whereabouts.

As they were breaking up for lunch, a volunteer called out to the group saying the pensioner had finally been found.

A set of footprints on a patch of muddy ground had led them to the fallen octagenarian, who was covered head-to-toe in mud and trembling after a night out in the frigid weather.

The rescuers wiped him down and bundled him up in thick clothing before rushing him to the Udon Thani hospital.

Kamchan's daughter Buachan Khunsomkan, 63, said: 'My father's third wife was worried because my father would always return home to sleep. She was worried because the weather was cold and was afraid that he might have been mugged by a group of teenagers.

'When they found him, he was so weak he couldn't speak. We brought him to the hut and washed him clean and gave him clothes to wear. He now feels a little better. The reason he fell was that he fainted due to an Ischemic Stroke.'

Kanchan's son-in-law Adul Somchit, 61, said: 'Kamchan removed his slippers and waded into the mud to look for fish but suddenly fainted and fell into the mud at around 3 pm.

'He was lying on his back when his friend Khun Yiam found him. There were even footprints near the scene. It's a miracle Kamchan survived. More than 20 people were looking for him.'

The family believe Kamchan, despite his age, survived the ordeal thanks to his hardy constitution, developed from his active daily routine.

Adul said: 'Kamchan cycles around and works in the paddy field every day. He used to sleep in the hut there, but when his third wife started suffering from Alzheimer's, he would come home every day to care for her.'

The family said they will keep an eye on Kamchan at all times following the incident.