Ankara, Oct 7 (IANS): Violations of Turkish airspace by Russian fighter planes deployed in Syria have raised alarm bells in Turkey, prompting NATO to issue a warning against Russia.

On Tuesday, the Turkish military issued a statement saying that a squadron of F-16 jets on patrol duty on Monday were radar-locked by a Russia-made MIG-29 over the Turkish-Syrian border, Xinhua reported.

The incident followed Russia's violations for twice of Turkish airspace over the weekend.

A Su-30 bomber crossed the Syrian-Turkish border for a few seconds on Saturday. Russia said the incursion was a mistake due to unfavourable weather conditions, adding that other alleged violations are under investigation.

NATO, however, said the Russian violation appeared to be deliberate.

On Tuesday, NATO Secretary-General Jens Stoltenberg called the airspace violation unacceptable. "It doesn't look like an accident, and we've seen two of them over the weekend," said Stoltenberg.

NATO defence ministers will be meeting in Brussels on Thursday to talk about NATO measures to respond to Russian actions in a member country.

"Both Russia and Turkey should be cautious in their moves and work to defuse the tension," Serkan Demirtas, a Turkish analyst, said.

Stressing that Syria has turned into a dangerous battlefield between the US-led coalition and the Russian camp, he said: "Any unwanted, unintentional development could lead to serious consequences that will surely have enormous effects on Turkey as well."

Turkey shares an approximately 900-km-long border with Syria.