A serious crash has shut the A1 near Borehamwood this afternoon.

Emergency services are at the scene of a collision involving a motorbike on the southbound carriageway.

It's believed to have happened at around 1.20pm.

According to witnesses, an air ambulance has landed in the area and an incident response unit has also attended, along with ambulances and police.

The A1 southbound carriageway has been closed by police between the M25 junction and the exit slip road at Borehamwood (Rowley Lane).

The northbound carriageway is open.

Motorists heading into London have been advised to use the M1.

Highways England posted on its website: "The A1 in Hertfordshire is closed southbound between the M25 J23 (South Mimms) and the A5135 (Borehamwood) due to a collision involving a motorcyclist.

"Hertfordshire Police are on scene with Ambulance Services. Highways England Traffic Officers are assisting with traffic management.

"If travelling to Wembley Stadium for this evenings match between England and Italy then please be aware. 

"There are no official tactical diversion routes however motorists are advised to exit the M25 at J21A and travel south on the M1 heading towards London."