Last year's finding of the Portuguese man o’ war. | R.L.

A number of Portuguese man o’ war have been spotted in the sea off Soller causing a great deal of local alarm.

The first was spotted on Sunday in the sea between Soller and Deya by a group of swimmers who were out sailing.

The first time Portuguese man o’ war were spotted in Balearic waters was on May 22 last year in El Molinar and over the course of last summer, others turned up off the Playa de Palma, Arenal, Pollensa, Sant Elm and Dragonera.

The marine authorities are investigating the sightings and monitoring their movements in the event of them posing a very real threat to swimmers.