Five Italian tourists — including a mother and daughter — have died after vanishing during a cave-diving expedition in the Maldives.

The group disappeared while exploring underwater caves about 50m deep in the popular Vaavu Atoll, south of the capital Male, on Thursday morning.

Among the dead were 55-year-old marine biologist Monica Montefalcone and her 20-year-old daughter Giorgia Sommacal.

The other victims were identified as Federico Gualtieri, Gianluca Benedetti and Muriel Oddenino.

Italian authorities said the divers were believed to have died while attempting to explore caves extending as deep as 60m beneath the surface.

The group had reportedly boarded the live-aboard diving vessel Duke of York before failing to return from the dive.

The alarm was raised about 1.45pm, sparking a frantic search involving speedboats and aircraft.

Maldives National Defence Force crews discovered a body inside a cave, with authorities believing the remaining four divers were trapped in the same underwater system.

The divers’ exact cause of death has not yet been revealed.

Police said rough weather may have contributed to the tragedy, with a yellow weather warning in place at the time and winds reaching almost 50km/h.

Universita di Genova expressed its “deepest condolences” following the deaths of two staff members connected to the institution.

Italy’s Foreign Ministry said consular assistance was being provided to the victims’ families through the Italian embassy in Sri Lanka.

Local officials described the disaster as the worst single diving accident in Maldivian history.

The Maldives is one of the world’s most popular diving destinations, attracting thousands of tourists every year to its reefs, caves and strong ocean currents.