Italian coast guard and navy ships rescue more than 2,000 people traveling in boats from North Africa in just 48 hours. (Reuters)

Italian authorities say they have rescued more than 4,000 would-be migrants at sea over the past four days as the war in Syria and instability in Libya spawn new waves of refugees.

The numbers of migrants reaching Italian shores generally rises this time of year as warm weather and calm seas make the Mediterranean crossing from North Africa easier. But the U.N. refugee agency said the numbers so far this year represent a 300 percent increase over the same period in 2013. Nearly 43,000 migrants arrived by sea in Italy in all of 2013.

Italian maritime officials said 2,922 people were picked up Monday and Tuesday, and 1,165 were rescued Wednesday and Thursday.

Italy has beefed up its air and sea surveillance of the sea smuggling route after a boat capsized in October off the Italian island of Lampedusa, killing more than 360 people. Lampedusa, in the southern Mediterranean Sea, is closer to the coast of North Africa than the Italian mainland, but it serves as a gateway to Italy and beyond for the refugees.

The spike in migrants is primarily because of renewed instability in Libya, where refugees from Syria and across Africa gather, awaiting a chance to buy passage on smuggling boats, said Carlotta Sami, a spokeswoman for the U.N. refugee agency in Italy.

In this photo released by the Italian Navy Thursday, March 20, 2014, migrants stand on a dinghy after being rescued along the Mediterranean sea. (AP/AP)

“They cannot stay safe in Libya,” Sami said, adding that the recent arrivals in Sicily included two Syrian women in their 80s. “Everybody is trying to escape Syria.”

The Syrian migrants would join tens of thousands of others seeking asylum in Europe and the United States. Syria’s three-year-old conflict generated 56,351 asylum seekers in 2013, more than double the 2012 total of 25,232, according to a report released Friday by the Office of the U.N. High Commissioner for Refugees.

Volker Turk, the agency’s director of international protection, forecast that Syria’s refugee problem would worsen this year.

Syria, Russia and Afghanistan had the largest numbers of people fleeing their homelands to seek asylum last year, the U.N. agency said. Russia was the source of 39,779 asylum seekers, up from 22,650 in 2012. And 38,653 Afghans sought asylum last year, vs. 47,519 in 2012.

The 38 nations of Europe had 484,600 asylum claims in 2013, 32 percent higher than in 2012. The United States dealt with 88,360 asylum applications last year.

— Associated Press