A six-year-old died earlier this week in what the Ministry of Health suspects to be a case of food poisoning.
A 13-year-old is also recovering at home suspected to have suffered the same misfortune.
The two girls, both from Kia Island in Macuata, were rushed to the Labasa Hospital four days ago because of the poisoning, which the Health Ministry has attributed to a new type of crab.
"We are advising the public to be cautious with the kind of food they eat. We are not stopping anyone from eating crabs or the kind of food they want to eat but just be cautious," ministry spokesman Shalvin Deo said yesterday.
"We have established that a new type of crab was eaten by the girls. The post-mortem (examination) will be done tomorrow (today)."
Divisional fisheries officer North Joji Vakawaletabua however said crab meat was not poisonous.
"This is the first time for me to hear about crabs being poisonous. It could be similar to the case in Suva where a nurse died after eating mana (mud crabs) sold at the Suva Market," he said.
"In that case, chemicals were used to catch crabs."
Mr Vakawaletabua said there were no new types of crabs.
"As far as we are concerned at the Fisheries Department, there is no new type of crab and the girls could have eaten something else that may have caused their vomiting," he explained.
"Crabs are not poisonous but are very nutritious and there is no new species of crabs in our waters."
A villager from the island, who wished to remain anonymous, said the girls were among a group of children who went out to sea to collect crabs and sea slugs.
"The children had their own buckets and filled it up with crabs and other sea slugs to sell in the market," he said.
"We suspect that the sea slugs kept in the same bucket could have released some toxin which affected the crabs that the girls ate.
"The two girls started vomiting after eating the crabs and while rushing the six-year-old to hospital in the boat, she died."