By Stephanie Nebehay

GENEVA, March 21 (Reuters) - Some 6,000 migrants have been rescued on the central Mediterranean between North Africa and Italy in the last few days, as greater numbers take that route in warmer weather, the International Organization for Migration (IOM) said on Tuesday.

The human tide seeking to reach Europe by sea - most of them sub-Saharan Africans - is mainly coming from Libya to Italy, after the deal between the European Union and Turkey a year ago largely shut down that route.

"We have yet to complete March, and we are already racing at a pace of arrivals that has exceeded anything we've seen before in the Mediterranean," IOM spokesman Joel Millman told a news briefing.

"This is typical of spring, getting very busy, but it's not typical to have the numbers be so high this early and the corresponding deaths that go with it."

Millman said some 500 migrants are believed to have drowned or been killed this year including 22 deaths just reported by the Libyan coast guard, compared to a total of 159 on the route last year.

Italian and European officials said on Monday they are ready to send equipment and economic aid to Libya to help fight traffickers who have thrived in a power vacuum left by the 2011 overthrow of former Libyan leader Muammar Gaddafi.

So far this year 16,248 migrants have arrived in Italy, up from 13,825 in the same period last year.

However, the overall number of migrants arriving in Europe, and particularly on Greek islands, has dropped substantially since the EU and Turkey agreed to prevent people making the crossing in return for financial and diplomatic incentives.

Across Europe, 160,331 migrants arrived by sea at this time last year compared to an estimated total of 20,484 arrivals so far this year, which includes those reaching Greece and Spain.

(Reporting by Stephanie Nebehay; Editing by Robin Pomeroy and Julia Glover) ((Stephanie.Nebehay@thomsonreuters.com; +41 58 306 2161; Reuters Messaging: stephanie.nebehay.thomsonreuters.com@reuters.net; twitter @StephNebehay))