Authorities have warned that Australia’s northern coastline is becoming a hotspot for ‘ghost nets’.

Ben Pearson from World Animal Protection told a national plastic pollution conference that plastic fishing nets, some the size of football fields, are appearing at an increasing rate in the Gulf of Carpentaria, where they pose a deadly risk to sea life including endangered turtles.

“These nets can be absolutely massive,” Mr Pearson said.

“They can weigh many tonnes and of course they're designed to catch marine animals, which is why they're so deadly.

“The turtles up there that are nesting and breeding are being caught in those nets and in some cases they're dying horrible deaths over many weeks.”

The nets are dumped by fishing boats when they become too damaged or tangled, allowing them to drift freely through the ocean as ‘ghost nets’.

Six of the world’s seven sea turtle species make their homes in the Gulf of Carpentaria, which is established as a major nesting area.

In 2016, Australian authorities found and removed 29 tonnes worth of ghost nets from the Timor and Arafura seas.

The nets also kill fish, affecting food security and reducing commercial fishing takes by up to 10 per cent a year.

Experts say they can last for 600 years in the marine environment.

But help could be on the way, with the CSIRO launching a project to work with Indigenous rangers from more than 30 communities to clean up the coast.

The authorities will also conduct an audit along 3,000 kilometres of the Gulf of Carpentaria next year to determine the scale of the problem.

A study in 2013 found at least 5,000 turtles had been entangled in more than 8,000 nets.