UPDATE: The northbound carriageway of the M1 has reopened after a suspicious object was found this morning.
The M1 northbound has finally reopened after more than eight hours.
It was closed while police and emergency services investigated a suspicious object under a bridge at Newport Pagnell.
The object was discovered not to contain explosives.
Thousands of drivers were stationary in queues for hours. The southbound carriageway is still closed.
Frustrated travellers played football, frisbee and touch rugby on the M1 after police closed the motorway for hours.
Thousands sat in gridlock from at least 8am, when Thames Valley Police closed the three-lane motorway between junctions 14 and 15 because of a "suspicious object".
Liz Searle, chief executive at the Keech Hospice in Luton, said she had been impressed by the good humour of everyone trapped on the side of the road.
"Everybody was being so helpful and chatty and high-spirited," she said, "which is lovely to see despite the circumstances."
Mrs Searle escaped the gridlock when police began to turn traffic around.
A spokesman for Highways England said the amount of traffic trapped was "down to about three or four kilometres" from a previous high of six kilometres, but could not comment on the details of the "suspicious object".
Thames Valley Police say investigations have revealed the object that's closed the M1 for seven hours does not contain explosives.
Investigation by the EOD [explosive ordnance disposal] can confirm that there is no explosive element to the object found," said Thames Valley Police in a statement.
Investigators are continuing a chemical analysis of the object to determine its make-up.
Aerial footage showed a bomb disposal robot dragging a black rubbish bag off the hard shoulder, which appeared to have contained a liquid and yellow substance.
Drivers on the M1 were trapped for hours as police dealt with a suspicious object spotted under a bridge near Newport PagnellRead the full story ›
A bomb disposal team has been seen making its way to the suspicious object on the M1 at Newport Pagnell.
The lorry went past stationary traffic on the motorway using the hard shoulder.
Traffic trapped on the M1 is being turned round so drivers can exit the motorway.
Highways England say it will take some time to release the drivers.
The road has been closed since just after 8am while emergency services investigate a suspicious object found under a bridge at Newport Pagnell.
Thousands of drivers are trapped within the closures on the M1 while emergency services work to investigate the suspicious object.
Chantelle Hambridge says she's been stationary on the M1 for one hour and 40 minutes.
Highways England says work to release the trapped drivers will begin as soon as possible but is warning it has not yet started and will take time when it does begin.
#M1 b/w J14-J15 we will look to clear any trapped traffic within closures ASAP, however this has not been started yet and will take time.
There are reports that some people have left their cars and are walking back to junction 14 to use services at Newport Pagnell.
Some drivers say the road appears to have reopened Northbound but is still stuck going South.
Drivers trying to use the M1 are facing five mile queues as police investigate a suspicious object found under a bridge at Newport Pagnell.
National Express says 45 minutes is being added to travel times and coaches are being diverted.
#M1 b/w J14-J15 remains closed due to police incident. Around 5 miles of queuing traffic on approach to closures-pls allow extra travel time
ROAD CLOSURE: M1 both directions J14 A509, J15A45/A508 due to a chemical spillage. Traffic congestion. 45min plus delays. Diversion in place
Police have confirmed the M1 has been closed while they investigate a suspicious object found under a bridge.
The road is closed in both directions at Newport Pagnell between junctions 14 and 15
Thames Valley police are urging the public to avoid the road.
They say a suspicious object was found underneath one of the motorway bridges between Junction 15 and 14 at around 7.30am this morning.
The M1 is currently closed in both directions between Junction 15 and 14, and diversions are in place in both Milton Keynes and Northamptonshire.
The road closures are likely to be in place for some time while Thames Valley Police and the fire service investigate the matter.
M1 currently closed in both directions between junction 15 and 14. Motorists urged to avoid the area at this time. More to follow.
The M1 is closed in both directions between Northampton and Milton Keynes as police deal with an incident.
The road's shut between junctions 14 and 15. There are reports that police are investigating an unknown chemical substance.
ROAD CLOSURE: M1-J15 A45 / A508 (Northampton) and J14 A509 (Milton Keynes). Stationary traffic due to police incident. Diversions in place.