Air force personnel attempted to bring down several drones spotted over the Volkel airbase on Friday evening, the defence ministry said on Saturday.

The drones were seen between 7pm and 9pm by security staff, who alerted air force personnel. Initially five drones were spotted, but the total later rose to 10, according to defence minister Ruben Brekelmans.

The ministry has declined to comment further on the incident or to say what weapons were used to try to bring down the drones. The drones flew off and none were found on the ground.

Brekelmans told told the AD that the decision not to give further details had been taken for security reasons so as “not to alert possible opponents to the type of weapons we use in such a situation.”

“Volkel is one of our most sensitive and best protected bases,” he said. The base is home to the Dutch F-35 fighter jets.

The defence ministry is now trying to establish “who or what” was behind the drones.

Unknown drones have been spotted over airports and military sites in Belgium, Germany, Poland, Lithuania, Romania, Norway and Denmark in recent weeks.

On Wednesday, drones were also spotted above Terneuzen port.