Police are investigating if power cables were deliberately brought down causing a blackout for thousands of homes and traffic gridlock on the A40.

The Witney bypass was closed after a tree landed on high voltage power cables causing them to sag on to the carriageway at about 11am yesterday.

Engineers spent almost six hours repairing the damage and restoring electricity to 1,500 homes around Witney.

The A40 was closed to traffic in both directions until 4.45pm at the B4022 Cogges junction and gridlocked traffic was forced to divert through Witney and surrounding villages causing gridlock.

Police are investigating a case of criminal damage after claims someone was spotted felling trees in woodland near to the A40 and seen driving a vehicle from the scene shortly after the power cables were damaged.

Spokesman Rebecca Webber said: “We had reports someone was tree-felling in woods shortly before the power line came down. Enquiries are ongoing to see what was happening at that time.

“We do not know who was responsible and appealing for anyone who was in the area at the time the cables came down to contact police.”

Police closed the A40 in both directions at around 11.10am.

Officers left the scene when Southern Electric engineers and Oxfordshire County Council took over at around 2pm.

Power was gradually restored to homes by 5pm.

Lorries and cars were forced to divert through Witney along Oxford Hill and Newland and via villages, including Freeland and Long Hanborough.

Geoff Payne, landlord of The Griffin, in Newland, said: “It’s been gridlock outside here all day long. Constantly throughout the day there has been slow moving cars and heavy good lorry stuck on this road outside. It’s all the way up Oxford Hill as far as the A40.”

Sue Partlett, of Cogges Hill Road, said “When I went out at 1pm the traffic coming down Oxford Hill was terrible.

“It was backed up all the way to the A40 as far as the eye could see and a lot of it was large lorries.”

Insp Paul Winks, head of Oxfordshire roads policing, said the closure caused mile long tailbacks on the A40.

“This incident caused considerable traffic congestion which was unavoidable in the circumstances,” he added.

“The main arterial routes in Oxford are at almost 100 per cent capacity for most hours of day so anything that affects the flow of traffic like this causes serious congestion.”

Anyone with information on tree-felling should contact police on 08458 505505 or Crimestoppers on 0800 555111.