The east tunnel on the A282 near the Dartford Crossing has been closed temporarily.
Highways England say this is because of essential emergency repairs to the road surface.
Two anti-clockwise lanes have also been closed because of the repairs on the J1A A282 / A206 / B3228 (Swanscombe) and J31 A1306 (West Thurrock).
Traffic has been stopped from using the M25 east tunnel which is causing more delays this morning.
The tunnel will be re-opened when it is "safe to do so", according to Highways England.
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