539 migrants were rescued from a fishing boat floating off the coast of Lampedusa by Italian coastguard vessels.

On Saturday, the rescue brought one of the greatest influxes of migrants to the Italian island in a single day.

Onboard were women and children. Some of the migrants, who were crossing the Mediterranean Sea from Libya, were said to have exhibited violent tendencies.

Prosecutors in Italy have launched an investigation into what may have transpired.

Alida Serrachieri, a doctor with the humanitarian organization MSF (Doctors Without Borders), said a number of the migrants seemed to have been physically beaten while waiting for a boat to carry them to Europe in Libya.

According to local media, investigators are looking into the probability that the migrants were wrongfully imprisoned in Libya.

The migrants were transported to Lampedusa by two coastguard vessels and a customs boat from Italy's financial crimes police, the Guardia di Finanza.

Toto Martello, the mayor of the island, called the rescue "one of the largest landings in recent years."

Lampedusa is a major entry point for migrants seeking to enter Europe.

More than 1,000 migrants arrived on the Italian island in a matter of a few hours in May.

A migrant camp on the island was built with the intention of housing no more than 300 people. It now has more than five times that number of people, with many more gathered on the dirt road outside.

The majority come from countries that are not qualified for asylum.