A terror alert that led to armed police stopping and evacuating a London-bound bus on the M6 was prompted by a passenger using an electric cigarette, police said this afternoon.
The security alert, which led to the closure of the M6 toll road, came after a concerned member of the public contacted police at around 8.20am this morning.
The coach was near the M6 toll plaza at Weeford, near Lichfield, when the passenger reported seeing vapour coming out of another traveller's bag.
Armed officers led passengers off the coach and the toll road was closed in both directions for more than four hours.
"The information received concerned a report of vapour escaping from a bag which on investigation turned out to be a health improvement aid for smokers," a force spokeswoman said.
No one was injured in the incident, there was no danger to passengers and no-one was being treated as a suspect police said.
"Given the credibility of the information we received, we responded swiftly and proportionately.
"We can now confirm that, whilst this was a genuine security alert, the significant concerns reported to us were unfounded."
She went on: "It's important to state that no criminal offence has been committed and no passenger or any other member of the public is being treated as a suspect.
"Our utmost priority was the safety and security of the public and whilst on this occasion the incident was resolved peacefully without event, we want to encourage the public to remain vigilant and report any suspicious activity.
"We would like to apologise for any inconvenience and hope that the public understand that we have our duty to safeguard public safety."
Overhead television pictures showed passengers being searched one by one.
Some, including at least one young boy, were surrounded by police in a cordoned-off area.
Pictures also showed decontamination areas, military personnel, police dog handlers, firefighters and other specialist units.
A spokesman for the bus company, Megabus - which is operated by Stagecoach, said
"We are assisting police with their inquiries into an allegation made against a passenger who was travelling on the 05.10 Preston to London service," she said.
"There were 48 people booked to travel on board the service, which was due to arrive at Victoria Coach Station in London at 10.55am.
"Police have confirmed that all passengers are safe and well and they have been transferred to a substitute vehicle.
"We are making arrangements to provide onward travel for passengers as soon as we receive clearance from the police."
Eyewitness Nick Jones, who was on the motorway at the time, told BBC News that police warned him to stay in his car, keep his windows closed and not to use air conditioning.
"I was beginning to feel a little uneasy," he said.
"I was beginning to look around for an escape route."
The passengers have now been allowed to continue their journey to London, although some have chosen to return to Manchester.