The Hatfield Tunnel on the A1(M) has been closed in both directions this morning due to safety concerns caused by a power related incident.

Engineers are currently on site and the tunnels - from Junction 4 to Junction 2 southbound and Junction 3 to Junction 4 northbound - will be re-opened when power has been restored.

Traffic is building southbound all the way from Hatfield to Junction 9 for Letchworth Gate.

Highways England advise local drivers using the road to expect disruption with extra journey time and possible re-routing.

Those coming from further afield are also advised to change their route.

The closure comes following a power cut which affected 76,000 Hertfordshire residents - in St Albans, Hatfield, Potters Bar and surrounding areas - at around 11pm last night.

UK Power Networks have said the power cut was due to a faulty piece of network equipment.

The power outage in the tunnel means that the safety features, such as smoke ventilation systems, cross tunnel doors and emergency lighting won't be operable in the event of an incident in the Hatfield Tunnel.

The tunnel has been closed in both directions as a precaution. Engineers are on site and are working to get the power up and running.

Drivers heading to the area from the north are advised to use the M11 and the M1. Clearly signed diversions are in place.

Those going south should follow the hollow triangle symbol from the A1(M) Junction 4 exit slip 'Clock' roundabout and take the third exit towards Hatfield/A1001.

At the next roundabout take the third exit towards St Albans/A1001. At the 'Galleria' roundabout take the second exit towards Conley Heath/A1001.

At the 'Roehyde' roundabout take the second exit heading towards London/ A1(M). At the next roundabout take the second exit to join the A1(M) junction 2.

Drivers heading northbound should follow the solid diamond symbol from the A1(M) Junction 3 and take the second exit on the 'Roehyde' roundabout towards Hatfield. At the 'Galleria' roundabout take the second exit. At the next roundabout take the third exit following directions for 'Motorway and Hertford A1001 (A414)'.

At the next 'Clock' roundabout take the second exit to re-join the A1(M) at Junction 4.