M4 westbound reopens after 'large diesel spillage'

4.50pm: The motorway has now reopened.

The M4 westbound between junction 12 for Theale and 13 for Reading is completely closed "for the foreseeable future" due to a large diesel spillage across the carriageway.

Highways England said all lanes westbound are currently closed.

A spokesperson for National Highways said: "The M4 in Berkshire is closed westbound between J12 (for Reading) and J13 (for Newbury) due to a large diesel spillage across the carriageway.

"National Highways Traffic Officers are on scene assisting with traffic management.

"Our contractors will also be attending to assess the damage to the road surface the the requirements for the clear up operation."

Thames Valley Police said on Facebook: "Officers are at the scene of an oil spill involving a coach on the M4 westbound near junction 12 (Theale).

"Junctions 12 (Theale) to 14 (Hungerford) westbound are currently closed while the emergency services deal with the spillage.

"We would ask motorists to avoid the area as the closure is likely to be in place for the foreseeable future and would like to thank them for their patience."

The incident has taken place near Ashampstead.