THE entry slip road to join the southbound carriageway of the M1 has been closed following a fire in a nearby scrap yard.

The motorway was sealed off at 4.30am, between Junction 4, A41 (Edgware), and Junction 1, A406 (Staples Corner), over fears that gas cylinders at the yard may explode.

Motorists will be unable to join the southbound carriageway at junction 5 (Watford).

Police who say the motorway could be closed for up to 24 hours to allow the cylinders to cool.