Two women and a girl believed to be migrants have been found dead with their throats slashed near Greece’s north-eastern border with Turkey, Greek authorities said.

The victims appeared to be of North African, Middle Eastern or Asian origin, but their nationalities and identities were unknown, police said. An initial examination of the bodies suggested the three were killed about four days earlier, coroner Pavlos Pavlidis said on Wednesday.

“It is clearly a criminal act,” Pavlidis told Associated Press. “They were found with their hands bound, each body about two or three metres away from the other. Their throats were cut right across.”

The woman appeared to be between 30 and 35 years old, the coroner said. One of the younger victims was aged 17-21, the other under 15, he said. DNA tests were planned to determine whether the three were related.

Police said a farmer found the victims on the Greek side of the river Evros, which runs between Greece and Turkey, east of the town of Didymoteicho. The Evros area is known as an entry point for migrants trying to enter Greece illegally by land.

Greek officials said the number of people arrested at the land border with Turkey so far this year was about double the total figure for 2017, although the sea route to the eastern Aegean Sea islands remains more popular.

Greece is a major entry point for refugees or economic migrants seeking better lives in Europe, with more than 24,000 arrivals so far this year. Most plan to continue on to more prosperous European countries, but are blocked by a series of closed borders in the Balkans.