Police and firefighters, backed by a boat and a helicopter, searched for the two women around the coast near Lloret del Mar, a popular resort some 70 kilometres (40 miles) northeast of Barcelona, local officials said.

Emergency services were alerted just after 4:00 am (0200 GMT) that the two women had not returned from a swim, the regional government of Catalonia said in a statement.

The rough sea, with waves of up to four metres (13 feet), prevented firefighters from carrying out an underwater search for signs of the missing women, who had been part of a group of five people, it added.

The national weather office issued an alert on Thursday for the coast of Catalonia because of the risk posed by the rough waters.

Elsewhere Spanish lifeguards in a helicopter rescued five crew members of a rowing boat that overturned in choppy waters some 50 nautical miles northeast of Mahon, the capital of the Mediterranean island of Menorca off the coast of Catalonia.

The three women and two men were in good health and were taken to Mahon airport, the maritime rescue service said in a statement.

The boat was taking part in a regatta at the time of the accident.

The maritime rescue service said the helicopter operation was “complex” since waves topped six metres at the time with winds of over 90 kilometres an hour.