Italian navy and coast guard vessels rescued more than 700 migrants in waters between Sicily and North Africa overnight as an immigration crisis that has cost hundreds of lives this month showed no signs of abating.

Patrol boats conducted five operations and those rescued included dozens of women and children, authorities said on Friday.

Several hundred were brought to an already overcrowded immigrant reception center on the southern island of Lampedusa.

Italian Prime Minister Enrico Letta has pressed European Union leaders meeting in Brussels to increase aid to Mediterranean countries including Italy, Greece and Malta which have handled the brunt of the crisis.

Italy has increased patrols in the seas between Libya, Tunisia and Italy since more than 360 mainly Eritrean migrants drowned in early October when their boat capsized off Lampedusa. A second boat sank a week later, leaving an estimated 200 people missing.

The island's reception center has struggled to deal with a deluge of migrants fleeing civil war and unrest in Syria, Egypt and other Arab and African countries, which has swelled numbers making the dangerous crossing of the Mediterranean sea, often on rickety and ill-equipped boats.

Over 32,000 migrants have made the journey to southern Italy by boat so far this year, according to the United Nations.