GENEVA (AFP) - More than 430,000 migrants and refugees have reached Europe via the Mediterranean since the start of the year, the International Organisation for Migration (IOM) said Friday, adding that nearly 2,750 had died attempting the trip.

The IOM said it had recorded 432,761 arrivals in Europe since Jan 1, comprising 309,356 in Greece, 121,139 in Italy, 2,166 in Spain and 100 on the island of Malta.

Last week, IOM had recorded 364,000 arrivals, but spokesman Daniel Szabo told AFP the numbers were revised upwards because the Greek government had significantly improved its counting methods in recent days.

The rising figures were not caused a sudden surge of migrants, he said.

Authorities in Greece opened an emergency registration centre on the island of Lesbos on Monday evening to clear a huge backlog of migrants that had built up.

On Thursday, Greek officials said some 22,500 had been registered on Lesbos already this week.