TAILBACKS on the M4 are playing havoc with rush hour motorists this evening following an overturned HGV westbound at junctions 8/9 (Maidenhead).

The incident occurred at about 12.45pm, affecting lanes one, two and three, causing the carriageway to be shut "for at least [the next] ten hours."

The driver of the HGV was rushed to hospital with serious injuries.

Disruption is severe on both sides of the M4 carriageway, with congestion stretching back as far as junction 11 eastbound (with one lane closed) and junction 7 westbound.

The accident is also causing a headache elsewhere as drivers scramble to find alternative routes.

The A404 northbound is experiencing moderate congestion between the M4 junction 8 and the A404 junction 9b (Thicket Roundabout), as is the A33 southbound between Bennet Road and Three Mile Cross.

A diversion route is in place along the A404, M40 and A34 but commuters are being urged to avoid the area completely.

Residents reacted with consternation to the news.

Former Strictly Come Dancing pro dancer Ian Waite tweeted to say he was caught up in the chaos.

"Stuck on the M4 in a traffic jam. Sadly an accident. Even an Air Ambulance has landed on the motorway," said Mr Waite, who teaches dance in Wokingham. 

Myra Katts wrote on the Thames Valley Police Facebook page: "It would have been nice if the diversion was marked!"

Valerie Kendall commented on the same page: "Could Thames Valley Police please petition the Highways Agency about this dangerous stretch of motorway, and ask that the planned "smart motorway" project be scrapped?"

"If the hard shoulder is removed along this stretch of the M4, there will be more accidents, and more lives lost."

Steve Bowles, an air cargo haulier at Heathrow, tweeted: "M4 is in a bad state [from] Junctions 8 to 11!

"If coming from the west get off at Newbury then head for M3 or M40."

A spokesman from Highways England suggested the carriageway would have to be closed for some time if there had been a diesel spill as a result of the incident.

"If there is a diesel spillage there is at times a requirement to resurface the road. It could be a protracted closure," he added.

A Thames Valley Police spokesperson said: "The westbound carriageway of the M4 at J 8/9-10 will be closed for at least ten hours.

"A diversion route is now in place along the A404, M40 and A34.

"Please avoid the area if you can."

The eastbound carriageway was also closed following the collision but has since reopened.