Turkey ordered an Armenian plane flying to the Syrian city of Aleppo to land today and authorities searched its cargo, as Ankara steps up efforts to prevent its air space being used to supply the Syrian military.
Turkey had previously been informed the plane, which was forced to land in the eastern Turkish city of Erzurum, would be carrying humanitarian aid.
Armenian officials knew it would be searched, an official from the Turkish prime minister's office said.
The plane would be allowed to continue on its journey if nothing else was found, a Turkish foreign ministry official said.
Turkey forced down a Syrian airliner travelling from Moscow last Wednesday and said it was carrying Russian munitions destined for Syrian president Bashar al-Assad's military, infuriating Moscow and Damascus.
Russia has said there were no weapons on the plane and that it was carrying a legal cargo of radar. But it moved to cool friction with Ankara - foreign minister Sergei Lavrov said the incident would not hurt "solid" relations.
Turkish foreign minister Ahmet Davutoglu said over the weekend Turkish air space had been closed to Syrian planes. Syria has also banned Turkish planes from flying over its territory.
Turkey has backed the rebels who have been fighting to end Dr Assad's rule since March last year, and says it won't turn a blind eye to arms shipments to Syria.
Tensions between the neighbours and former allies have escalated since a shell fired from Syria landed in a Turkish border town earlier this month, killing five people.
In June, a Turkish plane was shot down by Syrian forces in the east Mediterranean.
Agencies