The director of the Colonial Memorial Hospital in Fiji's capital says an antibiotic-resistant superbug can't be ruled out of the deaths of four babies.
The babies have died since the outbreak of Acinetobacter baumannii was confirmed in the neonatal intensive care unit.
The acting director, James Fong, said the babies died of other serious illnesses, but it can't be ruled out that the bacteria contributed to their deaths.
"They were admitted with very severe disease. They would not have acquired this bacteria if they had normal immunity. Yeah, it may have contributed to making it more difficult to treat," Dr Fong said.
Part of the unit remains quarantined and the government was working with international experts to try and combat the bacteria, but it could take at least six weeks.
Dr Fong said the bacteria was found in hospitals around the world, and the rest of Colonial Memorial remains safe, and parents should not be deterred from taking their sick children for treatment.
He said he's worried a shortage of supplies could have led to the outbreak of the superbug.
Dr Fong said authorities are looking into a number of possibilities including cross-contamination caused by a supply shortage.
"That's what we fear most and that's why we are investigating it more strongly. We are constantly struggling with this issue of consumables, that is a persistent issue."