More than 4,200 migrants trying to reach Europe have been rescued from boats in the Mediterranean in the past 24 hours, the Italian coastguard has said.

In some of the most intense Mediterranean migrant traffic of the year, a total of 4,243 people were saved from fishing boats and rubber dinghies in 22 operations involving ships from Italy, Ireland, Germany, Belgium and Britain.

The announcement on Saturday came a day after 17 bodies were found on one of the boats off Libya. The nationalities of the victims have not yet been released.

Migrants escaping war and poverty in Africa and the Middle East this year have been pouring into Italy, which has been bearing the brunt of Mediterranean rescue operations.

Most depart from the coast of Libya, which has descended into anarchy since western powers backed a 2011 revolt that ousted Muammar Gaddafi, and calmer seas and warm spring weather is encouraging departures.

Last month, about 800 migrants drowned off Libya when their 20m fishing boat capsized and sank. The accident led to the European Union agreeing a naval mission to target gangs smuggling migrants from Libya, but a broader plan to deal with the influx is in doubt due to a dispute over national quotas for housing asylum-seekers.

About 35,500 migrants arrived in Italy from the beginning of the year up to the first week of May, the UN refugee agency estimated, a number which has swelled considerably since. About 1,800 are either dead or missing.

Most of those rescued on Friday and Saturday are expected to reach ports in southern Italy during the weekend.

HMS Bulwark, the Royal Navy ship sent by the government to assist with search-and-rescue operations in the Mediterranean, took more than 740 migrants to the southeastern Italian port of Taranto early on Saturday.

European Union authorities have pressed member states to share the burden of housing refugees more fairly through a resettlement quota system.

However, an EU plan to disperse 40,000 migrants from Italy and Greece to other countries met with resistance this week. Britain said it would not participate and some eastern countries have called for a voluntary scheme.