Australians stranded in New Caledonia have been urged to exercise a “high degree of caution” after days of rioting that has brought the deaths of young indigenous Kanak and a police official.

France has declared a state of emergency on its Pacific island territory after rioting over electoral reform.

The state of emergency, which began at 5am local time on Thursday (4am AEST), gives authorities additional powers to ban gatherings and forbid people from moving around.

Police reinforcements adding 500 officers to the 1800 usually present on the island have been sent after rioters torched vehicles and businesses and looted stores.

Schools remain shut and there is already a curfew in the capital.

Australia’s Department of Foreign Affairs and Trade has also upgraded its warnings for anyone who is stuck on the island, with international flights grounded until at least Friday.

“Avoid demonstrations, public gatherings and roadblocks. Minimise movement, monitor the media and follow the advice of local authorities,” it said on Thursday.

“Exercise a high degree of caution in New Caledonia overall due to protests and travel disruptions. Higher levels apply in some areas.”

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Australians stuck in the capital of Noumea have shared “terrifying” encounters with protesters, as the situation escalates.

“The streets were on fire, there was rioting in the streets,” Mike Lightfoot told the Seven Network.

“Quite a frightening experience – as we approached one of the roundabouts, there would have been about 150 people rioting.”

The rioting is over legislation adopted by MPs in Paris on Tuesday, which will allow French residents who have lived in New Caledonia for 10 years to vote in provincial elections – a move some local leaders fear will dilute the Kanak vote.

“No violence will be tolerated,” Prime Minister Gabriel Attal said, adding that the state of emergency “will allow us to roll out massive means to restore order”.

He later signed a decree declaring a 12-day state of emergency and announced that French soldiers would be used to secure New Caledonia’s main port and airport.

Authorities have also banned video app TikTok.

The French government says it helped rioters organise and amplified the chaos, attracting troublemakers to the streets during riots in mainland France last northern hemisphere summer.

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Earlier in the day, a spokesperson for New Caledonia’s President Louis Mapou said three young indigenous Kanak had died in the riots.

The French government later said a 24-year-old police official had died from a gunshot wound.

“He took off his helmet [to speak to residents] and he was shot right in the head,” Interior Minister Gerald Darmanin said.

Noumea resident Yoan Fleurot told Reuters in a Zoom interview that he was staying home out of respect for the nightly curfew and was scared for his family.

“I don’t see how my country can recover after this,” Fleurot said, adding he carries a gun during the day when he goes out to film the rioters he called “terrorists”.

Police were outnumbered by protesters, locals told Reuters.

Electoral reform is the latest flashpoint in a decades-long tussle over France’s role in the mineral-rich island, which lies in the south-west Pacific, 1500 kilometres east of Australia.

France annexed the island in 1853 and gave the colony the status of overseas territory in 1946.

It has long been rocked by pro-independence movements.

New Caledonia is the world’s No.3 nickel miner and residents have been hit by a crisis in the sector, with one in five living under the poverty threshold.

“Politicians have a huge share of responsibility,” said 30-year-old Henri, who works in a hotel in Noumea.

“Loyalist politicians, who are descendants of colonialists, say colonisation is over but Kanak politicians don’t agree. There are huge economic disparities,” he said.

Henri, who declined to give his full name, said there was significant looting, with the situation most dangerous at night.

Witness Garrido Navarro Kherachi said she moved to New Caledonia when she was eight years old, and had never been back to France.

Although eligible to vote under the new rules, she said she wouldn’t “out of respect for the Kanak people”.

“I don’t feel I know enough about the history of Caledonia and the struggle of the Kanak people to allow me to vote,” she said.

-with AAP