Would-be beachgoers near Barcelona faced a brief ban after a shark scare shut down six beaches for a day, the Red Cross said on Wednesday.

Three small blue sharks, between one and 1.5 metres (five feet) long, were sighted by lifeguards on Tuesday, prompting two local town halls to ban bathing from their beaches.

The beaches in the resorts of Premia del Mar and El Masnou near Barcelona were closed on Tuesday and reopened on Wednesday morning, a local Red Cross spokeswoman told AFP.

“A surveillance patrol in boats did not find the sharks,” so green flags were flying again on Wednesday indicating it was safe to bathe in the sea, the spokeswoman said.

Two Red Cross boats carrying out routine patrols in the waters off the two resorts were continuing to keep an eye out for the sharks, she added.

The Florida Natural History Museum, which monitors shark attacks, says the blue shark is considered a dangerous species and is known to have attacked sharks and boats.