Drivers are advised there will be a full weekend closure of the northbound A1(M) in Hertfordshire for urgent road surface repairs from tomorrow (June 7). 

A defect resulting in a depression in the road surface requires excavation and reconstruction of part of the carriageway, National Highways has said.

The northbound carriageway will be closed between junctions 6  - The Clock at  Welwyn - and 7 - Langley Sidings/Stevenage South - from 9pm on Friday to 5am on Monday.

A spokesperson for National Highways said: "This section of the A1 runs over chalk and some watercourses, which is suspected as a potential cause.

"As this is in the same area as a repaired defect, we are also using this closure to carry out more investigations, to avoid future emergency closures. 

"We apologise for the inconvenience caused. Motorists are advised to plan ahead, allow more time for their journeys and follow signposted diversions." 

Since Sunday, one lane on the A1(M) northbound between junction 6 at Welwyn and junction 7 at Stevenage has been closed due to the defect.

In March, the same stretch of road was closed for more than a week while works were carried out to repair "a significant defect".