Police are warning of a 'large bump' under the surface of the Mountain Road which has appeared overnight.
The constabulary says it's developed on the Hillbery section of the highway on the Ramsey-bound carriageway.
Officers says the Department of Infrastructure has been notified and is assessing the cause.
They add, as a result, the area may be subject to to works in the following hours which may disrupt travel in the area.
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