The Ballybay Road from Monaghan Town will be closed for "at least" three hours this evening according to Gardaí.
It is believed that the road closure is in place due to a road traffic collision.
Gardaí were alerted following reports of a two vehicle collision shortly before 5pm on the Ballybay Road, Monaghan.
There are no reports of any serious injuries.
Meanwhile, local diversions are in place as Gardaí and local authority clear the scene.
Members of the public have been advised to avoid the area, due to heavy traffic.