Police evacuated 273 people from a Pakistani jet diverted to Stockholm due to a bomb alert Saturday and briefly detained a passenger after Canadian authorities received a tip that he was carrying explosives.
However, no explosives were found on the man, who was released after questioning by police, or on the Boeing 777 from Pakistan International Airlines, which had been bound from Toronto to Karachi, Pakistan.
The Royal Canadian Mounted Police said it was investigating whether the incident was a "terrorism hoax."
"If the information is deemed to be a hoax, the person who passed along that information can be charged for public mischief," said spokeswoman Sgt. Julie Gagnon in Ottawa.
All passengers — except the suspect — were allowed back on the plane at Stockholm's Arlanda airport nine hours later.
It took off for Manchester, England, from where the passengers would continue their journey to Karachi, said Jan Lindqvist, a spokesman for airport operator Swedavia.
Swedish police described the suspect as a Canadian citizen born in 1982. Initially they said he was of Pakistani background but later said they were not sure.
A prosecutor decided to release the man after questioning, and police were trying to help him continue his journey to Karachi either late Saturday or Sunday, police spokesman Erik Widstrand said, adding the man had cooperated with investigators.
"He was calm but irritated," Widstrand said.
"The suspicions against the man were not sufficiently strong for an arrest order and he is therefore free to leave Sweden," the prosecutor's office said in a statement.
The pilot asked to land the plane in Stockholm after Canadian authorities said they received a tip by phone the man was carrying explosives. Passengers were told there was a technical problem with the aircraft and didn't find out the real reason until they were on the ground, Widstrand said.
A SWAT team detained the suspect as he was evacuated from the aircraft along with the other passengers. An Associated Press reporter at the airport saw the passengers boarding yellow airport buses parked near the aircraft.
The tip was "called in by a woman in Canada," police operation leader Stefan Radman said, adding that Swedish police took the threat seriously.
Royal Canadian Mounted Police spokesman Sgt. Marc LaPorte said an anonymous caller called twice Friday saying a man on the flight had explosives.
"The first call provided vague information. It did lay out that there was an individual on that specific flight in possession of explosives and then the second call provided more details with regards to the identity of the person," LaPorte said.
He declined to elaborate on the caller, saying there was potentially a criminal offense involved.
"On its face" it appears someone had an ax to grind against the man, LaPorte said, but couldn't elaborate on the motive.
"If the Swedish authorities are saying that they released him and there is no investigation on their end, we will obviously pursue this as a hoax," LaPorte said, adding there could be a terrorism hoax charge as well as a public mischief charge.
In Washington, the FBI was assisting Swedish and Canadian authorities in their investigation, FBI spokesman Paul Bresson said Saturday.
Swedish police said the man was not on any international no-fly lists and had cleared a security check in Canada. He didn't resist when the SWAT team took him into custody.
In Pakistan, a spokesman for state-run PIA confirmed the incident involved Flight PK782 to Karachi.
The passengers waited at the "international holding area" at the airport as they and their luggage were scanned and searched, airline spokesman Sultan Hasan said. Pakistani diplomats were at the airport to coordinate with the security officials.
PIA said there were 255 passengers and 18 crew members on the plane. Of the passengers, 102 were Canadian nationals, 139 Pakistanis, eight U.S. citizens, three Indians and one each from Japan, Malaysia and Bangladesh.
The Canadian Embassy in Stockholm was in contact with local authorities to gather additional information, Foreign Affairs spokesman Alain Cacchione said.