Russia is demanding an explanation from Turkey after Turkish military jets forced a Syrian passenger plane to land in Ankara while it was flying from Moscow to Damascus.

Russia's foreign ministry said in a statement Thursday that Turkey's actions threatened the lives and safety of the passengers on board, which included 17 Russian citizens.

The Syrian Air flight with more than 30 people on board was allowed to complete its trip to Syria early Thursday, after Turkey confiscated what it called illicit cargo.

Turkish Foreign Minister Ahmet Davutoglu said Wednesday that authorities at Ankara's Esenboga airport seized items that violated international civil aviation rules.

Turkish television network NTV said the confiscated materials included missile parts. The Syrian government has not commented on the incident.

Turkish military jets had forced the plane to land in the Turkish capital on suspicion that it was carrying weapons from Russia to the Syrian government of President Bashar al-Assad, a longtime Russian ally. Mr. Assad has been fighting an 19-month uprising by rebels trying to end his 11-year rule.

Davutoglu said Ankara is determined to stop the flow of weapons to what he called a Syrian “regime that carries out brutal massacres” against its own people. Turkey is one of the strongest regional opponents of Mr. Assad and provides a haven to many of the rebels leading the uprising.

The Turkish foreign minister also said Ankara has banned Turkish passenger planes from entering Syrian airspace, deeming it unsafe.

Turkish troops have repeatedly shelled Syrian military targets in recent days in response to Syrian artillery that landed just inside Turkey. Turkish military chief Gen. Necdet Ozel said Wednesday that his forces will respond with “greater force” if Syrian shelling continues to spill across the border. He was speaking on a visit to the Turkish border village of Akcakale, where Syrian artillery killed five Turkish civilians last week.