KUNMING - Drones have been found at the clearance protection zone of an airport in Southwest China's Yunnan province, and local police are investigating.

Sources with Kunming Changshui International Airport in the provincial capital said Sunday that there were four or five incidents in the past two days of drones flying close to the airport.

"Regulations stipulate that unmanned balloons, kites, gliders and parachutes are not allowed within the clearance protection zone, about 1,028 square kilometers surrounding the runway," an official said. "Those who violate the regulations are subject to fines up to 100,000 yuan (about $14,600)."

The flying of drones could pose a threat to aviation safety, though the incidents reported did not disrupt flights at the airport.