Italy is in talks with other European Union states about sharing the burden of rescuing migrants crossing the Mediterranean in crowded boats from North Africa, senior officials meeting in Milan said on Tuesday.

So far this year, more than 63,000 migrants have arrived in Italy by sea, according to the UN refugee agency (UNHCR), surpassing the previous record of around 62,000 set in the whole of 2011, the year of the "Arab Spring" uprisings.

But more than 500 have died trying to make the perilous sea crossing, including 12 on Sunday when their boat capsized off the coast of the Libyan Tripoli, the UNHCR said on Tuesday.

That tragedy focused international attention on the desperate risks taken by many migrants, whose plight has been highlighted by human rights groups and Pope Francis.

Though about two-thirds of those who are rescued move on quickly to other EU countries, member states have so far offered Italy little help with Mare Nostrum, and Frontex has provided only limited air surveillance.

Italy - along with Spain, Greece and Malta - have been left mostly on their own to manage the growing number of migrants who seek to enter the EU in boats departing from North Africa, partly because increasing anti-immigrant sentiment in countries like Britain and France makes it unpopular to help out.

Most of the migrants who reached Italy by sea last year were refugees fleeing Syria's civil war and Eritrea's harsh military service, and the trend has continued this year, according to the UNHCR. Of the 12 confirmed dead on Tuesday, three were Syrian and three Eritrean.