A motorcyclist has been seriously injured following a crash at the Cotter Dam this afternoon.

At about 2.30pm, ACT Emergency Services responded to reports of a crash on Brindabella Road near the Cotter Dam.

ACT Ambulance Service paramedics with the assistance of South Care treated the man on scene before he was transported to hospital in a critical condition.

Brindabella road was closed for several hours between the Cotter Dam and Uriarra Township until the scene was cleared.

ACT Policing were in attendance and are investigating the cause of the crash.

Anyone who witnessed the incident, or who may have dash-cam footage is urged to contact Crime Stoppers on 1800 333 000, or via the Crime Stoppers ACT website.  Please quote reference 7430320.