EDIRNE, Turkey (AP) — A Turkish court on Monday rejected lawyers' request for two Greek soldiers arrested in Turkey to be released from custody.

The two were arrested last week for allegedly entering a Turkish military zone and on suspicion of attempted espionage. Greece said the two soldiers — a lieutenant and a sergeant — accidentally strayed into Turkey due to bad weather during a patrol of the Greek-Turkish border.

The development has added further tensions to already strained ties between the NATO allies.

Lawyers for the two Greek soldiers filed a demand Monday for their release at the court in the northwestern Turkish city of Edirne. The court however, ruled that they must remain in custody on grounds that they did not have permanent residence in Turkey and because the court was still examining the "digital data" seized from them, the state-run Anadolu Agency reported

Earlier in Athens, Greek Foreign Minister Nikos Kotzias renewed a demand for their swift release.

"Turkey must observe procedures prescribed by international law, and not turn a routine incident into a big political and legal issue," he said.

A river marks most of the Greek-Turkish border, while a fence runs along much of the land section. However, some parts aren't clearly marked.

Relations between neighbors Greece and Turkey have soured in recent weeks over longstanding disputes over boundaries in the Aegean Sea and natural gas drilling rights off the coast of war-divided Cyprus.

Last month, a Greek coast guard vessel was rammed by a Turkish patrol boat off disputed islets in the east Aegean, and Turkish warships prevented an exploratory gas rig from drilling near Cyprus.

"The main problem that we are facing in the region is called Turkey," Kotzias said. "It would be good for Turkey to respect international law and maritime law."