GENEVA (AFP) - More than 300,000 migrants have crossed the Mediterranean to Europe so far this year - far fewer than the 520,000 who arrived during the first nine months of 2015, the United Nations said Tuesday (Sept 20).

"The number of refugees and migrants reaching European shores this year passed the 300,000 mark today," William Spindler, spokesman for the UN refugee agency (UNHCR), told reporters.

Despite the lower numbers attempting the dangerous sea crossing, fatality were rates had risen, with 2016 on track to be "the deadliest year on record in the Mediterranean Sea", the agency added.

So far, 3,211 migrants have been reported dead or missing on the Mediterranean in 2016, just 15 per cent lower than the total number of fatalities for all of last year (3,771), a UNHCR statement said.

Different patterns have emerged in the two European countries, Greece and Italy, which receive the vast majority migrants.

Arrivals in Italy this year stood at 130,411, on a par with the 132,000 people who landed over the same period in 2015, according to UNHCR.

But Greece has seen a 57 per cent drop in arrivals this year, with numbers falling since a March deal between the European Union and Turkey on curbing migrant flows across the Mediterranean.

Nearly half of the migrants and refugees who landed on Greek shores this year were Syrians, UNHCR said.