BRUSSELS — More than 6,000 migrants have been rescued in the Mediterranean Sea in recent days while attempting to make the dangerous crossing from North Africa to Europe, an official said Tuesday, marking the resumption of a stubborn flow of people fleeing poverty and war.

The surging figures suggest that growing numbers of migrants, refugees and others –many from Africa and the Middle East – are trying to make the sea passage to Europe as the weather warms and smugglers increase operations.

The influx of people has become a major political issue in Europe, as anti-immigrant populists crusade against mainstream leaders and look to capture power in France and make gains in Germany in elections this year. European Union leaders have signed deals with Libya and some of the sub-Saharan countries that are sources of most of the current flow, but the root causes of the migration are as intractable as ever.

The Mediterranean has become the main corridor for migrants trying to reach Europe aboard smugglers’ boats from Libya and elsewhere after authorities largely choked off sea routes between Turkey and Greece last year.

But the dramatic spike in Mediterranean rescues since late last week suggests even greater migrant traffic ahead, said Joel Millman, a spokesman for the Geneva-based International Organization for Migration, which monitors migrant flows and provides direct aid in refugee camps, detention centers and elsewhere. “This is typical of spring, getting very busy,” he said. “But it’s not typical to have the numbers be so high this early and the corresponding deaths that go with it.”

An estimated 500 migrants have drowned in the Mediterranean this year, and more than 20,000 have been intercepted at sea and brought to Italy and other European ports since January, Millman said. He said that if current trends hold, the traffic across the Mediterranean will be higher than it was last year but lower than in 2015, the peak year.