Rescue operation for the Friday's shipwreck in waters between Malta and Italy which left more than 30 migrants dead were one of the toughest, a rescuer said on Saturday.

"I have been doing this sort of work for 10 years but this was one of the most difficult operations for me personally," Major Russel Caruana, captain of the Maltese army vessel which first reached the migrants' capsized boat on Friday evening, told local media.

"There was a large number of people who were floating motionless,"he said after his crew disembarked 143 survivors onboard the Maltese ship on Saturday morning.

A heavily overloaded boat with more than 200 migrants capsized in the Maltese search and rescue area on Friday afternoon. At least 33 people were reportedly dead.

"It was very tough, partly because of the great distance that we were operating from and the rough weather, but also because there were so many people in the sea. We have done many operations of this sort but this situation was more dramatic than usual," he said.

A crew from his patrol boat reached the people on south east of Malta with a dinghy and launched a life raft which on its own rescued some 60 people.

Eventually, the Maltese vessel took aboard some 150 survivors while some, including a mother and her infant, were evacuated by helicopter to Italy's southern island Lampedusa due to their urgent medical condition. The Armed Forces of Malta (AFM) also brought to Malta the bodies of four people - two toddlers, a 11-year-old boy and a woman.

Among the survivors, who are all believed to be Syrian refugees, is a month-old baby and a couple, who lost track of their three children.

"There are two sets of parents who had children but while one couple saw their children being taken on board an Italian vessel, the others have no idea whether their children are dead or alive," a source with access to the migrants told timesofmalta.com.

Social workers, who were accompanied by Social Solidarity Minister Marie-Louise Coleiro Preca, were also given access to the refugees, and they are expected to receive more bodies recovered by Italian and Maltese patrol boats on the scene.

The migrants said they left Libya and paid between 3,000 and 4,000 U.S. dollars per person for a place on the boat.

Asked if he could ascertain why the boat had capsized, Major Caruana said it was too early.

Meanwhile, the Italian navy is involved in another two rescue operations one involving a boat with 180 people on board, the other with 170.

More than 300 people drowned when a boat carrying Eritrean and Somali migrants sank near Lampedusa just last week.