Seven foreign tourists have been taken to hospital after drinking pia coladas at a five-star resort in Fiji, with methanol poisoning not yet ruled out.

On Monday, Fijian health authorities said Australian and American holidaymakers staying at the Warwick Resort, on the island’s Coral Coast, had fallen ill with nausea, vomiting and seizures following a cocktail on Saturday.

The cause is not yet clear, but Viliame R Gavoka, Fiji’s tourism minister, told reporters nothing could be ruled out until police received the toxicology results, expected to take three or four days.

Mr Gavoka said five of the seven people affected had now been discharged, while there were no reports of similar illnesses at the resort or elsewhere in Fiji.

He said: “The resort management has assured us that they have not engaged in practices such as substituting ingredients or altering the quality of drinks served to guests,” adding that the hotel “holds a strong reputation”.

The minister said that “this is the only reported case of its kind that we’ve experienced in recent memory, and certainly nothing like this has been experienced this year”.

But the case has raised alarm following the deaths of six people, including Simone White, a British lawyer, from methanol poisoning in Laos last month after they drank free shots at a hostel in Vang Vieng.

David Sandoe, whose daughter Tanya and granddaughter Georgie were taken to hospital on Sunday evening, told the Australian channel 9News that the thought of events in Laos “sends shivers down your spine” and said he was “having nightmares”.