Distressing photos have emerged online of a beached whale in Indonesia that was found to have almost six kilograms of plastic in its stomach.

The sperm whale washed up on the shore of Kapota Island, in the Wakatobi Archipelago of Southeast Sulawesi, Indonesia on Monday.

The grim discovery was posted online by Whale Stranding Indonesia, an organisation that tracks incidents of mammals washing up onshore in the region of Indonesia.

Photos posted on the organisation's Facebook page show an array of plastic items that were present in what was thought to be the whale's stomach.

19112018 a code 4 sperm whale stranded on Kapota Island Wakatobi SE Sulawesi. A 5.9 kg debris found inside d whale. The dominant debris are raffia and plastic cups. News: Mr Hardin (DKP Wakatobi). Photo: Mr Alfi (AKKP-KKP). Tx 2 Kartika Sumolang (WWF)



FB: https://t.co/zPukshy6at pic.twitter.com/uk7wTS71AH — Strandings Indonesia (@stranding_ID) November 19, 2018

However, it admits that decomposition of the body means it is uncertain that the organ cut open was in fact the stomach.

According to the Facebook page: "soft plastic, hard plastic, plastic bags, plastic cups, bottled drinks, sandals and raffia" were among the items that spilled out of the stomach when it was cut.

In the photos, single-use plastic cups can be seen amongst the items, as well as what appears to be a large, jagged shard of a plastic plate.

After weighing the contents of the stomach, the organisation claims a total of 5.9 k.g of plastic was present in the stomach. This was mainly made up of plastic cups and raffia (a fibrous, man-made material).

The Wakatobi Marine and Fisheries Community Academy is said to be investigating the discovery.

After seeing the photos, Greenpeace issued an urgent warning to cut our single-use plastics.

Louise Edge, Greenpeace UK oceans campaigner, said:

"If nature had a distress signal to warn us that it can't take any more of our plastic rubbish, it would look like this - a dead whale with 1,000 pieces of plastic in its stomach.

"Our throwaway culture has turned whales' guts into dustbins for our plastic waste. And the global plastic contamination doesn't end there - this material is already in the food we eat, the water we drink, and inevitably in our bodies too. It's clear that we can't go on like this.

"If we want to stop this slow-motion environmental disaster unfolding before our eyes, we need to immediately start cutting the amount of throwaway plastic we produce."

She added the source of the problem is at the manufacturing stage, calling on big food companies to reduce single-use plastic out of their production lines.

Research suggests there are more than five trillion pieces of plastic in the ocean, which poses a severe threat to marine wildlife.

Recent studies have found the plastic being swallowed by marine animals is making its way back into the human food chain, with plastic particles being found in human bodies after eating fish.