A deer has been found dead in Thailand after swallowing 7kg (15lb) of plastic bags and other rubbish, raising the alarm on littering in the country’s waters and forests.

The south-east Asian country is one of the world’s largest consumers of plastic, with Thais using up to 3,000 single-use plastic bags each per year, whether for wrapping street food, takeaway coffee or packing groceries.

Marine animals like turtles and dugongs have died in its waste-choked waters, and autopsies have found that plastic in the stomach lining contributed to their deaths.

Officials said a 10-year-old deer was found dead in a national park in Nan province, around 630km (390 miles) north of capital Bangkok.

An autopsy discovered “plastic bags in the stomach, which is one of the causes of his death”, said Kriangsak Thanompun, director of the protected region in the Khun Sathan national park.

A vet weighs the waste found in the deer. Photograph: HANDOUT/Office of Protected Area Region/AFP via Getty Images

The bags contained coffee grounds, instant noodle packaging, garbage bags, towels and also underwear, according to photos provided by the national park.

The discovery of the deer comes months after a sick baby dugong won hearts in Thailand as she fought for recovery, only to pass away from an infection exacerbated by pieces of plastic lining her stomach.

The demise of Mariam in August was widely mourned on social media, reviving public debate on Thailand’s urgent need to tackle its plastic addiction.

The loss of the wild deer is “another tragedy”, Kriangsak said.

“It shows we have to take seriously and reduce... single-use plastic,” he said, calling for “nature-friendly products” to be used instead.

Several major retailers – including the operator of the ubiquitous 7-Eleven convenience stores – have pledged to stop handing out single-use plastic bags by January next year.