Turkish fighter jets have forced a Syrian passenger plane to land at Ankara's airport for investigation, Turkish state media report.The plane, which was travelling from Moscow, was intercepted on intelligence that it was carrying "non-civilian cargo", Turkey's foreign minister said.
He added that Turkey was determined to stop any transfer of weapons to the Syrian government through its airspace.
Turkey has made clear its support for the rebels in Syria's civil conflict.
The plane, which is reported to be carrying 35 passengers, was escorted by Turkish jets to the capital's Esenboga airport for security checks, Turkish news agencies reported.
The passengers have been escorted off the aircraft while the cargo is searched.
US task force Turkish Foreign Minister Ahmet Davutoglu told state-run television that Ankara had received information that the plane could be carrying "certain equipment in breach of civil aviation rules".
Meanwhile, the Turkish authorities have declared Syrian airspace to be unsafe and are preventing Turkish aircraft from flying over the country, the foreign ministry said.
The move comes as Syria and Turkey continue to exchange artillery fire on their border.
Earlier on Wednesday, Turkey's top military commander warned Syria that Ankara would respond with greater force if Syria continued its cross-border shelling.
Five Turkish civilians were killed by Syrian mortar fire last week, prompting Turkey to fire into Syria for the first time since the uprising against President Bashar al-Assad began 19 months ago.
Meanwhile, the US has confirmed reports it has established a military task force in Jordan.
It is monitoring the security of Syria's chemical and biological weapons as well as helping with the aid effort.