Indonesian officials are waiting for permission from the family of a dead Queensland mum and her daughter to perform an autopsy.

Indonesian authorities say their investigation into the sudden deaths of a Queensland woman and her teenage daughter at a Bali resort is expected to take longer than usual.

Noelene Bischoff, a nurse from the Sunshine Coast, and her 14-year-old daughter Yvana died in the early hours of Saturday, a day after checking into the beachfront resort of Padang Bai in Karangasem, on Bali’s east coast.

Their relatives have been told toxic fish may have caused their deaths.

The head of Denpasar Police Forensic Laboratory Agus Budiartha said it could take longer than a week to determine the cause because forensic officers have a lot of samples to examine, including medication found in their room.

“There are lots of samples from the vomit, the medicines and the drink,” he told AAP.

“Since they’re all abroad medicines, from the country where they’re from, we might have some difficulties because it’s not what’s usually used in Indonesia.”

Ms Bischoff and Yvana ate a mixed seafood lunch on Friday at the Warung Dewa Malen restaurant, a popular eatery with Australian tourists in Ubud, around 50km from Padang Bai.

Later that day the pair checked into their hotel and ate seafood again for dinner – this time mahi mahi fish at the Buddha Bar and Restaurant attached to the resort.

About six hours later, Yvana reportedly begged for help from security staff, saying she and her mother had fallen gravely ill.

Ms Bischoff died while being transported by ambulance to a local medical centre and Yvana died at the Bali International Medical Clinic in Denpasar.

Ms Bischoff’s mother Jean Bischoff said the two were very close.

“The biggest blessing we’ve had out of it, that they went together, because one wouldn’t have been able to live without the other,” she told the Nine Network.

The resort’s hotel manager Giovanni Bareato said he and a group of others had also eaten the same fish that night.

“It’s a big fish so we would have eaten the same one,” Mr Bareato told AAP.

“We haven’t fallen ill and I know of no-one else who have fallen ill from the food.”

He said he did not believe the fish was toxic and a doctor had told him he suspected the mother and daughter had a food allergy.

However, Jean Bischoff said they had no food allergies whatsoever.

“They could eat anything and everything,” she said.

A waitress from the Warung Dewa Malen Restaurant who served Ms Bischoff and her daughter said she didn’t see any signs of illness and doesn’t believe they had a food allergy.

She said Ms Bischoff had shrimp, tuna and squid and her daughter ordered fried calamari.

“When I asked how’s the food, they said it was good. And they ordered a lot, the whole course until dessert. They were happy,” waitress Gusti Ayu Mentari Dewi told AAP.

Food safety consultant and microbiologist Dr Patricia Desmarchelier says it’s an unusual case, however it’s possible the pair may have died from toxic fish, including a condition known as ciguatera poisoning.

“People usually don’t die, at least in western countries, of food poisoning,” Dr Desmarchelier told AAP.

“To have two people die so quickly like that is unusual but not necessarily impossible.

“But what it does suggest is that they have had massive doses of toxins.”

Ciguatera poisoning is contracted by eating warm water ocean finfish, like mahi mahi, that carry the ciguatera toxin produced by a tiny organism attached to algae.

Symptoms, including vomiting, muscle pains and headaches, usually start an hour to 24 hours after eating a toxic fish.

Indonesian officials say they are yet to perform an autopsy as they haven’t been given permission from the family so far.

Under Indonesian law, an autopsy can proceed without permission from Tuesday.