A dead sperm whale with nearly 6 kilograms of plastic waste in its stomach has been found on a beach in central Indonesia, a national park official said Wednesday.

Park Chief Heri Santoso said the 9.5-meter-long rotting carcass was found Monday washed ashore a tiny island in Wakatobi National Park, a marine national park in Southeast Sulawesi.

(Supplied photo)

A team from the Wakatobi Marine and Fisheries Community Academy later found 115 plastic cups, four plastic bottles, two flip-flops, a nylon sack containing over 1,000 pieces of string, and other plastic debris in its stomach.

Putu Liza Mustika, coordinator of nongovernmental organization Whale Stranding Indonesia, said the dead whale looked thin and suspected that the plastic debris contributed to its death.

Jenna Jambeck, a researcher at the University of Georgia in the United States who studies plastic marine waste, said in research published in the journal Science in 2015 that Indonesia was the world's second-largest plastic polluter after China.

According to Jambeck, Indonesia produces 3.2 million tons of mismanaged plastic debris every year, of which 1.29 million tons ends up in the ocean.