FURIOUS motorists are demanding to know why they were left stranded on a Hampshire motorway after it was closed for more than 11 hours.

The M3 near Winchester was closed in both directions on Saturday as police and bomb disposal experts examined a “potentially hazardous material” that was found in the carriageway between junctions 9 and 11.

Last night it emerged that the drama had been caused by nothing more dangerous than a piece of flammable material thrown from a bridge.

But the resulting road closure caused a day of gridlock on the motorway and surrounding routes, including Winchester city centre.

Warnings were issued by Highways England - but motorists caught up in the chaos described the organisation’s response to the incident as “too little, too late”.

Many said they were already approaching the Winchester section of the M3 when they learned that the road ahead was shut.

By then it was too late to leave the motorway. Instead of enjoying a relaxing day out they found themselves staring at the vehicle in front for hours on end as the seemingly endless queue of traffic inched its way towards the next exit.

Motorists marooned in the huge tailbacks said Highways England should have issued stronger warnings over a wider area.

Highway bosses said they used a raft of measures to alert drivers but Steve Brine, Tory MP for Winchester, pictured left, is demanding answers.

He said: “Saturday’s incident on the M3 was a nightmare.

“I’m asking Highways England for a full explanation of how they handled the closure.”

Some drivers said it took them three hours to travel ten miles. Those diverted off the M3 at Winnall then took an hour to negotiate the roundabout, with motorists switching lanes and blocking yellow junction boxes.

Writing on social media Jim Hall said: “Stuck at Winchester Services. If the road has been closed since 4am, why did they let us on if there’s no way of getting off?”

Others shared images of families leaving their stationary cars and sitting on the central barrier.

Hundreds of football fans on their way to the Saints v Manchester United game at St Mary’s were among those caught up in the congestion.

Scott Sartin tweeted: “Any chance of delaying KO? It’s my son’s birthday and we are stuck in severe delays due to M3 closure.”

Manchester United fans are reported to have left their coach and made the two-mile journey to Winchester railway station on foot.

Motorist Jenna Keating, 31, from Windsor said: “There are lots of people stranded.

“People have got out of their cars to stretch their legs but some are turning round and going back down the hard shoulder.

“We actually spoke to police about this to see whether it was something we could do in the circumstances and they said absolutely not.

“They also said the delay had been quite well advertised, although none of us in the car saw anything until we were in it.”

A Highways England spokesman defended the organisation, saying he was driving along the M25 on Saturday when he saw an overhead sign saying the M3 was closed.

He added: “As soon as we were made aware of the incident we set strategic signs and signals informing drivers of the closure.”

In a statement the organisation said it used Twitter, the Traffic England website and bulletins on local and national radio to alert drivers.

A spokesman for Hampshire-based motoring organisation the AA added:

“It’s a question of what action Highways England took and when they took it.”

Last night police confirmed the events of Saturday were not being treated as a terrorist incident.

A spokesman said: “Early assessments indicate this was a flammable, not explosive, material which had been thrown from the motorway bridge which leads to St Catherine’s Hill.

“We recognise that this caused extensive disruption for members of the public going about their daily business.

“We would like to assure them that public safety was our top priority as we investigated matters.”