LONDON — A British warship in the Mediterranean launched a mission to rescue at least 500 migrants on Sunday, the Ministry of Defense said in a statement. The MoD said a helicopter had identified four migrant vessels in distress. “HMS Bulwark has now commenced rescue operations to recover those in the vessels,” the statement said. On Saturday, more than 2,000 migrants were rescued from five wooden boats in the Mediterranean and as many as seven other vessels have been reported at sea, the privately funded Migrant Offshore Aid Station (MOAS) and Italy's coastguard said. The boats — nine wooden boats thought to be converted fishing vessels and six large rubber dinghies — were all found drifting around 45 miles off the Libyan coast after issuing distress calls via satellite phone on Saturday morning, the coastguard said. Boats from the Italian, German and Irish navies took part in the rescue operation, which was coordinated in its initial stages by MOAS, a privately-funded rescue operation operating out of Malta in partnership with the Doctors without Borders (MSF) charity. The exact number of migrants rescued was put at 3,480 by the coastguard and there were no reports of casualties. One Italian navy boat which was ferrying 475 migrants to Sicily reported that it had seven pregnant women amongst its human cargo. The number of migrants attempting to reach Italy on boats organized by people traffickers has increased by over 10 percent in the first five months of 2015, suggesting last year's figure of 170,000 migrants landing in Italy will be surpassed. Nearly 1,800 migrants are thought to have drowned attempting to make the crossing since the start of this year, including some 800 in one sinking that was the biggest maritime disaster in the Mediterranean since World War II. That disaster prompted European governments to significantly increase search and rescue operations between Italy and North Africa but they have been unable to agree on a longer-term strategy to ease the migration crisis which aid workers blame on conflicts that have created more displaced people around the world than at any time since the end of WWII. — Agencies