A group of 300 sub-Saharan Africans (R) sit in board a boat during a rescue operation by the Italian Finance Police vessel Di Bartolo (L) off the coast of Sicily, May 14, 2015. Around 1100 migrants were rescued off the coast of Sicily, about 130 miles from Lampedusa, according to the police. [Photo/Agencies]

Boko Haram, which has killed thousands in its attempt to carve out an Islamist state, has suffered major setbacks this year following a co-ordinated military offensive by Nigeria, Niger, Chad and Cameroon.

A German ship, Italian navy vessels, a merchant ship, and Italy's finance police and coast guard all conducted rescue operations on Thursday, a coast guard official said.

The 40-meter Phoenix, based in Malta and run by the Migrant Offshore Aid Station (MOAS) and Doctors Without Borders, rescued 561 people, including 136 women and 60 children, mostly from Eritrea. The ship picked up 188 people on Wednesday.

The surge in rescues comes just a day after the European Union announced a plan to distribute asylum-seekers more fairly around its member states and take in 20,000 more refugees.

At the beginning of the month when the weather also was favourable, about 6,800 people were rescued over three days, while dozens were said to have drowned.

With the estimated number of migrant deaths at sea this year approaching 2,000, and after as many as 800 died in a single shipwreck last month, the EU has bolstered its Triton sea mission to help Italy conduct the rescues.