An eight-month-old dugong, nurtured by marine experts after being found lost near a beach in southern Thailand, has died from what biologists believe was a combination of shock and ingestion of plastic waste.

Key points: Marium was cared for after being chased and apparently attacked by a male dugong

Marium was cared for after being chased and apparently attacked by a male dugong An autopsy revealed a large amount of plastic waste in the animal's intestine, an official said

An autopsy revealed a large amount of plastic waste in the animal's intestine, an official said The Thai Environment Minister says the death will remind people not to dispose of rubbish in the ocean

The female dugong named Marium became popular in Thailand after images of biologists embracing and feeding her milk and seagrass spread across social media.

Marium had been found bruised after apparently being chased and attacked by a male dugong during mating season, Jatuporn Buruspat, director-general of the Department of Marine and Coastal Resources, said.

She was brought in for treatment in the artificial sea on Libong Island in Krabi province.

Veterinarians and volunteers had been setting out in canoes to feed Marium up to 15 times a day while also giving her health checks.

An autopsy showed a large amount of plastic waste in the dugong's intestine. ( AP/Sirachai Arunrugstichai )

"We assume she wandered off too far from her natural habitat and was chased and eventually attacked by another male dugong, or dugongs, as they feel attracted to her," Mr Jatuporn said on Saturday.

An autopsy showed a large amount of plastic waste in her intestine, which could also have played a part in her death as it led to gastritis and blood infection, he said.

"She must have thought these plastics were edible," Mr Jatuporn said.

The animals, which are a vulnerable species, can grow to about 3.4 metres in length.

Marium's corpse will now be stuffed. ( AP/Sirachai Arunrugsticha )

Natural Resources and Environment Minister Varawut Silpa-arcpha said the dugong's corpse would be stuffed.

"Her death will remind Thais and people all over the world not to dispose trash into the oceans," he said.

AP