Greek officials fears that the spring weather will bring another influx of refugees and migrants from Turkey to islands already overrun with 15,000 of them were shown right when the head of the European Union’s border patrol Frontex said there had been a 17 percent hike in the previous five weeks up to May 1.

Fabrice Leggeri told a German daily newspaper the spike is being driven by new waves of people fleeing war and strife and Syria, Iran and Iraq, who go to Turkey in hopes of reaching the EU, which has closed its borders to them.

Turkey is letting human traffickers operate even during a suspended swap deal with the EU, dumping the problem on Greek islands where human rights groups said people are being kept in detention centers and camps in inhumane conditions.

He said the EU needs a better border protection plan as Turkey has taken back only a relative handful deemed ineligible for asylum in Greece, where they are stuck, unable to to move on to other countries and not wanting to go back to their troubled homelands.

The United Nations refugee agency UNHCR said 2,900 people also came by foot through the eastern Greek province of Evros across from the Turkish border in April, most from Syria and Iraq, a number half the land arrivals in all of 2017 and with more coming by sea from Turkey to islands, particularly Lesbos, Chios and Samos.

“It’s too early to know the causes of the increase … more time is needed to say if the flow really is shifting,” said Izabella Cooper, a spokeswoman for Frontex, which has a staff of only 26 officers in the area.

Refugees and migrants are taken to police facilities for identification and then sent to to detention centers although some try to get to Thessaloniki or Athens if they can afford it.

Greece’s highest court said newly-arriving refugees and migrants can’t be held and are free to go anywhere in the country but the ruling Radical Left SYRIZA has refused to obey the court order and government officials aren’t being made to do so.

“Hundreds of people are at present being held in police detention facilities,” the UNHCR said, the Turkish newspaper Hurriyet and other media said they were told.

Another senior officer, speaking on condition of anonymity, said they can barely keep up with arrivals. “The reception center is full to capacity … there is a great increase in flows, but the situation is still under control,” he told Agence France Presse.

Cooper said the agency is ready to divert additional resources to the area if requested without explaining why it hasn’t been yet. “Our operations are flexible and we are ready to increase our presence if necessary,” she told the Greek daily Ethnos.

Most of the migrants illegally crossing to Europe are male, according to data provided by Frontex, some 40 percent families and almost all those from Morocco said to be young males.