Some 522,000 migrants have made the dangerous crossing across the Mediterranean so far this year, the International Organization for Migration (IOM) reported Tuesday in Geneva.
More than 388,000 of them went by boat from Turkey to Greece, while 131,000 ventured from Northern Africa to Italy.
Smaller numbers have arrived in Spain and Malta.
“Even if arrivals are still increasing, it is necessary to emphasize that this in not an emergency in terms of numbers,” IOM director general William Lacy Swing said in New York, pointing to the 4 million Syrian refugees being hosted by Middle Eastern countries and Turkey.
Europe should create legal channels for migrants so that they do not have to turn to people smugglers and their boats, he said.
Nearly 2,900 people have died this year trying to cross the Mediterranean, according to IOM.
An estimated 1,151 migrants were pulled from boats off the coast of Libya on Monday in 11 rescue operations by Italian authorities, according to Ansa news agency.
The migrants were transported to the Italian ports of Lampedusa and Pozzallo.
On Monday, the European Council announced the second phase of the EU operation to tackle the surging numbers of migrants crossing the Mediterranean, and renamed it Operation Sophia.
From October 7, officers “will be able to board, search, seize and divert vessels suspected of being used for human smuggling” in international waters, it said.
The first phase focussed on dealing with the influx of migrants, and only allowed voluntary boarding of vessels.
The second stage, which aims to reduce the capacities of people smugglers, was approved in mid-September but was held up while contributing states mustered the resources.
The operation was renamed Sophia from EUNAVFOR, after a baby girl born to a Somali migrant during a rescue by a German vessel.
Most of the migrants arriving in Greece are making their way to neighbouring Macedonia, across the Balkans, and on to Austria and Germany.
Three quarters of the 103,000 arrivals who have been registered in Macedonia since June were from Syria. A tenth was from Afghanistan, according to IOM.
Further west in France, authorities told broadcaster iTele that a 20-year-old migrant from Iraq was found dead in a truck near the port of Calais.
The city is one of the main crossing points for migrants and refugees trying to reach Britain. Twelve people are estimated to have died trying to cross the English Channel this summer.