ATHENS, Greece — Greece is seeking assistance from the European Union, NATO and the United Nations' secretary-general in securing the release of two Greek soldiers who were arrested in Turkey after they strayed across the border, government officials said Tuesday.

Prime Minister Alexis Tsipras spoke by telephone with United Nations Secretary-General Antonio Guterres about the soldiers' arrests last week, the Greek government said.

A Turkish court in the border city of Edirne has rejected a request for their provisional release.

Greek Defense Minister Panos Kammenos said Tuesday in Brussels that the soldiers, a lieutenant and a sergeant, were arrested a "few meters" inside Turkish territory while on a patrol against migrant smuggling. He briefed European Union defense ministers.

Federica Mogherini, the EU foreign affairs and security chief, said the EU continued to advise Turkey to show "good neighborly relations" and hoped for a "swift and positive outcome" to the incident.

The arrests have further strained relations between the two NATO allies who have longstanding disputes over maritime boundaries and commercial rights.