Police were called to the scene at around 4.30 pm after the incident. They advised motorists to stay clear of the area before closing the road all together at around 5 pm.
Writing on social media the force said: ‘Two vehicle RTC in the Tunnel, Emergency Services enroute, delays likely, please use alternate route.’
They later added: ‘The Tunnel is now closed due to earlier RTC.’
No further details have been released.