A child holds a bottle of water as he walks in a temporary camp, in the Italian island of Lampedusa on October 4.
A migrant boat capsized between Sicily and Tunisia on Friday and hundreds of people were in the sea, the Italian navy said, and the national news agency ANSA said corpses had been spotted.
The incident came just over a week after at least 319 people drowned when a boat carrying Eritrean and Somali migrants sank near the southern Italian island of Lampedusa.
"There are at least 200 people in the sea and our helicopters are picking them up," said a navy spokesman, adding that two navy ships were also on the scene.
Maltese authorities were co-ordinating the rescue operation, which was in Maltese waters, and a Maltese ship was on the scene, a Maltese navy spokesman said.
The boat sank only around 70 miles (120 km) off Lampedusa and survivors would be taken there, he added.
Last week's disaster was one of the worst in a long migrant crisis that has seen tens of thousands of people arrive in flimsy, overcrowded boats in southern Italy, and some vessels wrecked. Lampedusa, a tiny island midway between Sicily and Tunisia, has borne the brunt.
According to the United Nations High Commissioner for Refugees, 32,000 have arrived in southern Italy and Malta this year alone, around two thirds of whom have filed requests for asylum.
Earlier on Friday at least 500 more migrants in at least three separate boats arrived or were rescued on the way to different parts of Sicily.
Most migrants come from sub-Saharan Africa, but this year many are fleeing the Syrian civil war or political turmoil in Egypt and other parts of North Africa. Many are drawn by hopes of finding work in Europe and often do not stay in Italy.
© Thomson Reuters 2013