Planes flying over Clydebank have been targeted by laser pens.
Police said there were two incidents last week of major commercial aircraft having laser beams shone at them from the town.
Shining lasers at aircraft endangers the lives of passengers and crew as the beam can distract pilots and obscure their vision.
The first incident involved an Airbus A320 British Airways flight from Heathrow coming in to land at Glasgow Airport.
The plane was carrying 168 passengers and six crew members.
A laser beam was shone at the aircraft from Beardmore Street, Dalmuir at at 10.15pm last Thursday.
Just twenty minutes later a laser beam was shone from Miller Street in Central Clydebank at a second plane.
The flight was a Boeing 737 arriving from Warsaw, Poland, with 184 passengers and six crew members on board.
Inspector David Quinn, based in Clydebank, said: "It is a criminal offence to attempt to distract the pilot of an aircraft and there is an element of danger.
"We will be putting additional patrol in place in areas underneath the flightpath in an attempt to prevent this."
A Glasgow Airport spokeswoman said: “Shining a laser pen at an aircraft is not only extremely dangerous, it is also a criminal act. We would urge anyone who witnesses a laser being shone at an aircraft to contact the police immediately.”
Police are appealing for anyone with information to contact them on 101.
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