ATHENS (Reuters) - More refugees and migrants crossed into Greece over its land border with Turkey than came by sea in April, the United Nations refugee agency (UNHCR) said on Friday, calling on the Greek authorities to improve reception facilities there.

The agency said some 2,900 people arrived in Greece through the Evros river crossing so far this month, most of them Syrian and Iraqi families. That equals half the estimated arrivals for 2017 overall, the agency said.

Nearly a million refugees and migrants crossed from Turkey to Greece’s islands in 2015, but that route all but closed after the European Union and Ankara agreed a deal to stop the flow in March 2016.

Under the deal, anyone who crosses to the Greek islands must qualify for asylum or face deportation to Turkey. The land border does not fall under the agreement.

Arrivals from Evros, a fast-flowing river which divides Greece from Turkey in the far northeast, have picked up in recent months. At least eight people have died this year.

UNHCR said the reception facility in the area was full beyond its 240-person capacity, including 120 unaccompanied and separated children. It said lack of space meant hundreds were being held in police detention facilities.

“Conditions are dismal and services are limited,” UNHCR said in a statement.

Families in one facility were sleeping on the floor beside a row of cells. Among those held were pregnant women, very young children and people in need of medical care, it said.

Greece’s island camps remain severely overcrowded, in some cases holding twice the number of people they were built for. Greece’s migration minister said arrivals there had also picked up since March.