ISTANBUL -- Turkish state-run television TRT reported Thursday that a Syrian passenger plane intercepted by Turkey's air force was carrying military communications equipment, as Damascus branded the incident piracy amid growing tensions between the two countries.

Yeni Safak, a newspaper close to the Turkish government, reported there were 10 containers aboard the plane, some containing radio receivers, antennas and "equipment that are thought to be missile parts."

Neither TRT nor the newspaper cited sources for their reports, and Turkish officials have yet to provide details on what was aboard the Syrian Air A320 from Moscow that was forced to land in Ankara on Wednesday.

Turkey's Foreign Minister Ahmet Davutoglu said the cargo contained "elements ... that are not legitimate in civilian flights" and insisted Ankara was within its rights to intercept the plane if it suspected that military equipment was being transported over Turkish territory.

But Syrian Transportation Minister Mohammad Ibrahim Said said Thursday that Turkey's decision to force the plane to land amounted to piracy.

The general manager of the Syrian Civil Aviation Agency also blasted Turkey's forced landing of the plane, calling it "contrary to regulations and aviation norms."

Ghaidaa Abdul-Latif told reporters in Damascus that the plane's pilots were not asked to land but were instead surprised by Turkish F-16 fighter jets, which forced them to land.

"This action is contrary to the rules, because the pilot should be first asked to land for inspection," she said. "If he refuses, military jets would then fly to force him to land."

A Syrian Airlines engineer who was aboard, Haithan Kasser, said armed Turkish officials boarded the plane and handcuffed the crew before inspecting packages that contained electrical equipment.

Abdul-Latif said the officials seized some packages after presenting official documents.

She said Syria would file a complaint with international aviation authorities.

Sabre rattling between Syria and its northern neighbor has increased in recent days after a spate of cross-border shell and mortar firings. Turkey, which has been vocal in its criticism of Syrian President Bashar Assad's crackdown on the opposition, has beefed up its military presence along the 565-mile (910-kilometer) frontier after shelling from Syria killed five Turkish civilians in a border town last week.

The plane incident has also increased tensions between Turkey and Russia, one of Syria last remaining allies.

Russia's ITAR-Tass news agency quoted an official at the Russian Embassy in Ankara as saying that the cargo "was not of Russian origin." Rosoboronexport, which handles most of Russia's military export contracts, said none of its cargo was on the plane.

Meanwhile Russian Foreign Ministry spokesman Alexander Lukashevich said Russia was concerned that "the lives and safety of the passengers, among whom were 17 Russian citizens, had been endangered."

He said Turkey without explanation denied Russian consular officials and a doctor access to the passengers, who had not been allowed into the airport for eight hours or provided with food.

"The Russian side continues to insist on an explanation for the Turkish authorities' actions toward Russian citizens and on the adoption of measures to avoid such incidents in the future," Lukashevich said in a statement.

The plane's 37 passengers and crew were allowed to continue to Damascus after several hours, without the cargo.

Also Thursday, Turkey's Energy Minister Taner Yildiz announced that Syria had stopped buying electricity from Turkish suppliers about a week ago.

"The door is open. If they request (electricity) again then we could resume providing it," Yildiz told reporters, adding that it was Syria's own decision.

Yildiz said Turkish companies supply around 2.3 billion kilowatt hours of electricity per year. The electricity amounted to some 18-20 percent of Syria's needs, he said.

He did not say why Syria had halted purchases, saying only "It was an agreement between Syria and the companies."