The number of migrants arriving in Greece dropped 90 percent in April, EU border agency Frontex said on Friday, in a sign that a deal with Turkey to send back those who make the sea journey between the two countries is working.

Frontex said 2,700 people arrived in Greece from Turkey in April, most of them from Syria, Pakistan, Afghanistan and Iraq, a 90 percent fall from March.

Under the deal with Turkey, all migrants and refugees, including Syrians, who cross to Greece illegally across the sea are sent back.

In return, the EU takes in thousands of Syrian refugees directly from Turkey and rewards it with more money, early visa-free travel and faster progress in EU membership talks.

In Italy, 8,370 migrants arrived through the longer and more dangerous route from northern Africa, Frontex added, with nationals of Eritrea, Egypt and Nigeria accounting for the largest share on this route.

Frontex said there was no sign of migrants shifting from the route via Greece to the central Mediterranean route.

The number of people arriving in Italy in April was 13 percent lower than in March and half of that of April 2015, Frontex added.