Authorities in the Spanish tourist hotspot of Benidorm said Friday they have reopened its beaches to tourists after removing more than a tonne of dangerous jellyfish.

The authorities posted red flags on the beaches on Wednesday after strong currents brought shoals of the creatures close to the shore of the Mediterranean resort.

The head of the city's department of the environment, Mariola Fluvia, said the beaches were reopened after workers removed the jellyfish on Thursday.

"Currents are pushing the jellyfish away from our shores" and municipal authorities "want to reassure bathers and users of our beaches because we hope that during the day (the jellyfish) will move away completely from our shores," the municipality said in a statement.

Shoals of drift close to Spanish Mediterranean shores every year.

Experts say increasing numbers can be a sign of rising but that overfishing of their also plays a part.

A fishing village 50 years ago, Benidorm today is a mass of skyscrapers, fast-food outlets, bars and nightclubs where tourists, mostly northern Europeans, come on cheap package holidays.