Turkish warplanes have shot down a Syrian helicopter after it entered Turkish airspace. The incident is bound to ramp up tension on an already volatile border. The Syrian army says its military helicopter "mistakenly" and "briefly" entered Turkey's airspace.

Turkey says the Syrian military helicopter entered two kilometers into Turkish airspace at 14:20 Monday local time.

Turkey also says warnings went out before taking action.

"It was repeatedly warned by our air defense elements. When the violation continued, our planes hit the helicopter at 14:25 with a missile, causing it to fall on Syrian soil," Turkish Deputy Prime Minister Bulent Arinc said. "So far, we have no information about the crew, as it fell on the Syrian side of the border."

The Syrian Observatory for Human Rights says rebel fighters have captured one of the pilots, while the fate of the other is unclear.

Turkish Foreign Minister Ahmet Davutoglu has described the shooting down of the Syrian helicopter as a "punishing operation," and stressed that Turkey would not accept any violation of its borders.

"I would like to repeat that Turkey, we have said it before, will not accept any incursion on its territory," said Turkish Foreign Minister Ahmet Davutoglu.

Shells from the Syrian conflict have occasionally rained down on the Turkish side of the 900-kilometer border.

Following Syria's downing of a Turkish jet in 2012, Turkish Prime Minister Tayyip Erdogan said the military's rules of engagement had changed. Any Syrian element approaching the border would be deemed a threat and be treated as a military target.