The police and the medical authorities are investigating the sudden death of a Spanish woman, aged 57, at Mater Dei Hospital early on Saturday.
The woman was in Malta on holiday with her husband and had apparently been perfectly healthy before being taken ill on Friday, after eating a fish salad in a restaurant.
An autopsy proved inconclusive and further tests are being held.
An inspection has reportedly also been made at the restaurant where the couple dined.
A magisterial inquiry is under way.