A sperm whale has been found dead in Indonesia with 115 plastic cups and 25 plastic bags in its stomach, raising concern among environmentalists and throwing the spotlight on the country's rubbish problem.

The items were part of nearly 6kg of plastic waste discovered in the 9.5-metre carcass, when it washed ashore in Wakatobi National Park in Southeast Sulawesi province on Monday.

Other debris included flip flops and ripped tarpaulins, the head of Wakatobi tourism told AFP.

Debris inside the whale included flip flops and tarpaulins (Pic: WWF-Indonesia/Kartika Sumolang)

Conservation group WWF Indonesia said on social media that its staff found four plastic bottles and 3.26kg of raffia rope, as well as the plastic bags and cups.

The exact cause of the whale's death is not yet known, but there are signs that "plastic waste might have triggered it", the WWF Indonesia marine species conservation co-ordinator said.

Wakatobi district, a picturesque collection of four main islands surrounded by a marine reserve, has urged Indonesia's central government to help tackle the problem of marine debris.

Indonesia is the world's second biggest contributor to marine debris after China, and a colossal 1.29 million metric tonnes is estimated to be produced annually.

The problem has grown so bad that Indonesian officials declared a "garbage emergency" last year after a 6km stretch of coast along the island of Bali was swamped with rubbish.

The exact cause of the whale's death is not yet known (Pic: WWF-Indonesia/Kartika Sumolang)

The archipelago of more than 17,000 islands has pledged to reduce marine plastic waste by 70% by 2025.

It plans to boost recycling services, curb the use of plastic bags, launch cleanup campaigns and raise public awareness.

But poor waste-processing infrastructure and low awareness among its 260 million inhabitants prove to be major obstacles.