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Traffic was halted on the approach to the Dartford Tunnels after a power outage in the area.
Delays quickly built up on the anticlockwise carriageway with tailbacks stretching to the M25 junction 2 turnoff for the Darenth Interchange.
Officers from Highways England attended the scene and power was restored shortly before 3pm.
All traffic has been released, clearing the 1.4 miles of congestion.