A grandfather was decapitated by a crocodile while dumping freshly-cut grass into a river in Indonesia.

Khalifah Anwar, 70, had just finished mowing his yard and walked to the Bangko River behind his home to dispose of the rubbish in Riau on April 23.

He decided to cool off in the water after the chore, unaware that a hungry crocodile was stalking him under the surface.

While the pensioner was bathing, the ravenous beast was said to have latched onto him before spinning its body rapidly in a death roll, tearing him to pieces before feeding on him.

Khalifah was reported missing after his grandson Nursalim visited his home that evening, only to find his house empty.

AKBP Isa Imam Syahroni, public relations head of the Rokan Hilir Regency police, said: 'The victim disappeared while bathing in the river behind his house in Jalan Penghulu Usman, Bangko Kiri Village, Bangko Pusako District, Rohil Regency.

'His neighbours last saw him at 3:30 pm, dumping grass on the riverbank where his red towel was found.'

Villagers and the local search and rescue unit trawled through the river on Wednesday evening, but the search was soon suspended due to poor visibility.

They resumed the operation on April 24 morning, deploying six rubber boats to expand the search area.

Footage shows volunteers scouring the river lined with dense forests.

At 1:40 pm local time, they discovered Khalifah's head drifting in the murky dark-green water. His heart was also found nearby, but the rest of his body was missing.

Ipda Dahri Iskandar Lubis of the Bangko Pusako District Police said: 'His head and heart were finally found in the Guru Zainal Cantik Road project ditch in Bangko Kanan Village.

'He will be buried this afternoon after the arrival of his child who is living in neighbouring Malaysia.'

Following the gruesome attack, authorities warned villagers to be careful when carrying out activities along the Bangko River, which was a known habitat of estuarine crocodiles.

The Indonesian archipelago is home to 14 types of crocs - with a large population of extremely large and violent estuarine crocodiles that flourish in the region's climate.

Conservationists believe that crocodiles have been driven further inland closer to villages due to overfishing reducing the crocodiles' natural food supplies combined with habitat loss from the development of coastal areas into farms.

Widespread tin mining has also caused villagers to encroach on the crocodiles' natural habitats, pushing the creatures closer toward people's homes.

With uneducated locals in the developing country still using rivers for bathing and primitive fishing, the deadly combination of factors has led to rising numbers of crocodile attacks.