A motorway has been closed in both directions following a major crash.

National Highways said the M4 in Berkshire was closed eastbound, between junctions 11 and 10, and westbound, between junctions 8/9 and 11, because of a “serious injury incident involving an overturned vehicle” on the link road from the motorway to the A329M.

South Central Ambulance Service confirmed it had five critical care units and six ambulances at the scene near Reading on Sunday afternoon.

Thames Valley Air Ambulance, Royal Berkshire Fire & Rescue and Thames Valley Police were also there, National Highways said.

Just before 16:00 BST, police said the closure would likely be in place “for the foreseeable future” and asked drivers to avoid the area.

National Highways described the crash as “major” and said there were “severe” delays approaching the closures in both directions, partly because of broken down vehicles in the queues.

The BBC has contacted Thames Valley Air Ambulance and Royal Berkshire Fire & Rescue.