Australians are undergoing treatment at a Fiji hospital after consuming cocktails at a local five-star resort, as the Pacific island nation’s government insisted the incident was “extremely isolated”.

Four Australian women, aged between 18 and 56, were among seven people sent to hospital after drinking at a bar at the Warwick Resort on Fiji’s Coral Coast on Saturday.

Jemesa Tudravu from the Fiji Ministry of Health said the patients were suffering from nausea, vomiting and “neurological symptoms”.

“We don’t have the cause of the incident yet, but our team is currently investigating,” he said, adding that separate toxicology tests were being undertaken by the Fiji Police Force.

A statement from the Fijian government said all seven guests had been transferred to the Lautoka Hospital for “medical care, investigation, and management”.

“We are glad to hear that they are stable and hope their conditions continue to improve,” said a statement from Fiji’s deputy prime minister and Minister for Tourism, Viliame Gavoka.

“This is an extremely isolated incident, affecting only these seven guests at a specific bar within the resort,” he said.

The ABC was told that some of the guests started having fits, chills and tremors after drinking pina coladas at the Warwick Resort.

Australian travel advice for Fiji updated

The Australian government overnight updated its travel warning for Fiji, warning travellers to look for the potential risks of “drink spiking and methanol poisoning” when consuming alcoholic drinks.

Carmel Marasco, a guest at the resort from Melbourne, told the ABC she was “quite upset” about the incident.

“I’ve been to the Warwick four times, I think, with my children and family, and it has never happened before,” she said.

“I was sitting there the same day, drinking the same cocktail.”

Federal minister Jason Clare told ABC News Breakfast on Monday morning that the incident in Fiji was “terrifying news”.

“There’s a real terrifying sense of deja vu, it’s only a month ago two young Australian women died in Laos from methanol poisoning,” Mr Clare said, referring to the deaths of Bianca Jones and Holly Bowles last month.

“When we wake up to hear this horrific news in Fiji, I’m sure all Australians have their heart in mouth and are hoping for the best.”

A Department of Foreign Affairs and Trade spokesperson said consular assistance was being provided to two Australian families in Fiji.

Three other people, understood to be two US nationals and a Fijian, also fell ill after drinking at the bar on Saturday night and were being monitored.

Mr Gavoka, Fiji’s deputy prime minister, said that being a tourist in the country was “typically very safe” and that the government sought to reassure international tourists that it was a “very isolated incident”.

“As we approach the festive season, we always advise everyone to exercise the usual caution about what they consume,” he said.

Earlier, the Warwick Resort told the ABC it was still operational after the hospitalisation of its guests.

“We don’t have anything to disclose because the resort is under investigation,” the resort’s reception said.