A Syrian military helicopter crashed near the Turkish border on Monday, a monitoring group reported, adding that there were conflicting reports about what brought it down.

The Syrian Observatory for Human Rights said some of its sources reported that the helicopter was shot down from across the Turkish border while others said Syria's rebels were responsible.

The private Turkish Dogan news agency said that the helicopter exploded in the air and then fell to the ground, 400 metres (yards) from the Yayladagi district of Hatay province on the border with Syria.

The Britain-based Observatory said a helicopter "that was being used to launch explosives-laden barrels" crashed in the Jabal al-Akrad area, a rebel stronghold in coastal Latakia province.

Some fighters claimed downing the helicopter, while others said a "warplane believed to be Turkish" had shot it down.

Observatory director Rami Abdel Rahman said the helicopter had landed on the Syrian side of the border and that rebel fighters had captured one of its two pilots.

The second pilot's fate is unknown, he said.

Neither Ankara nor Damascus has commented officially on the incident.

Syrian activists meanwhile distributed amateur video showing the helicopter as it fell, while a second video showed the two pilots landing by parachute.

"Don't shoot!" calls out an unidentified man in the video, while another man is heard saying: "The helicopter's on the ground."

Rebels battling President Bashar al-Assad's forces have frequently shot down helicopters and warplanes used by the air force to pound opposition areas.

Relations have deteriorated between Damascus and Ankara, who were once close allies, since the outbreak of an anti-Assad uprising and the unleashing by the regime of a brutal crackdown against dissent in March 2011.

Turkey has since then consistently lobbied for Assad's downfall and has deployed NATO Patriot missiles along its border with Syria.