The Hatfield Tunnel on the A1(M) has fully reopened, following its closure this morning due to a power cut.

The power failure affected 76,000 domestic dwellings in Brookmans Park, Hatfield, London Colney, Potters Bar, St Albans and beyond last night, with Highways England announcing at 6.37am this morning that the tunnel had been closed in both directions as the outage was affecting safety features.

READ MORE: Huge delays on A1(M) as Hatfield Tunnel closed due to power failureHighways England said it could keep essential services up and running thanks to its two generators, but had to close the tunnel as a safety precaution.

"The outage in the tunnel means that safety features, such as CCTV, smoke ventilation systems, cross tunnel doors and emergency lighting won't be operable in the event of an incident in the tunnel," a Highways England spokesman told this paper.

The closure - lasting more than seven hours - had seen huge delays in both directions during rush hour, with diverted traffic causing jams in and around Hatfield, Welwyn Garden City and St Albans areas.