Spanish emergency services picked up 470 immigrants travelling in dozens of rafts across the Strait of Gibraltar on Tuesday and 227 from the same stretch of water the day before, a spokesman for the Maritime Safety Agency said.
More than 75,000 have tried to cross the Mediterranean from North Africa, landing in Italy, Greece, Spain and Malta, the UNHCR agency says, with about 800 people dying in the attempt.
About 10,500 children, two-thirds of them unaccompanied or separated from their families, were included in those numbers, as people flee violence in Africa and the Middle East, often using unseaworthy vessels and with the help of smugglers.
On Tuesday, some 49 boats carrying mostly men, but also 68 women and 15 under-18s, made the journey from North Africa to the south of Spain, Spanish authorities said. It was not clear whether the boats were in difficulty when they were stopped.
The Mediterranean shipping lane is almost 15 km (9 miles) wide at its narrowest and is often used by migrants, crowded onto rafts and tiny fishing boats, trying to get to Europe.
The number of people trying to get to Europe across the Mediterranean is already about 60 percent higher than the whole of last year, the U.N. refugee agency said in July.
The rush in the last 48 hours may be due to calm seas and warm weather. Increased security around the North African Spanish territories of Melilla and Ceuta is also likely to have pushed people to the coasts, local Spanish media said.
More than 700 people tried to scale the razor-wire barriers in Melilla on Tuesday, the government said, of which only 30 reached Spanish territory where they will be either repatriated or sent to the mainland Spain.
Reporting by Rodrigo de Miguel