People smugglers managed to disembark some 400 migrants, probably all Tunisians, from two boats near a beach in Sicily on Sunday before sailing away, the Italian news agency ANSA reported, citing police.

The incident sparked a helicopter search for their vessels.

The report said the boats dropped the migrants off a few metres (yards) from shore near the historic town of Agrigento in southern Sicily.

The coastguard backed by a helicopter were searching for the boats, ANSA said.

The migrants left the beach in small groups, setting off across the island, local press reports said.

Some stopped motorists to ask for water or for a ride, the Agrigento Notizie daily said.

The local mayor told reporters the migrants were likely all Tunisians after speaking to some of them.

Such a large group of arrivals in Sicily has not been seen in years, with human smugglers increasingly avoiding Italy.

Some of the migrants rounded up wait by the roadside along with police. Photo: AFP

Smaller groups, mostly from Libya, are frequent arrivals.

Italian authorities said 52 people, mainly from sub-Saharan Africa, arrived Sunday aboard a boat no more than 10 metres (35 feet) long on the small island of Linosa near Italy's southernmost island Lampedusa.

According to interior ministry figures as of Friday, 4,445 migrants have arrived in Italy since the start of the year.

A separate boat carrying 78 people, including women and children, was in Malta's search and rescue zone on Sunday, according to NGO Alarm Phone.