A Ryanair flight from Oslo to Manchester has been evacuated after two passengers were thought to have used the word "bomb" during an argument in an airport toilet.
The pair were taken for questioning by police at Norway's Rygge airport on Sunday evening and a bomb squad searched the aircraft but found nothing suspicious.
Police spokesman Anders Stroemsaether told a Norwegian public broadcaster that the incident began before boarding when two foreign passengers were overheard arguing and other passengers thought they heard the word "bomb" being used.
"After questioning of witnesses and those brought in, the police have concluded that the situation is a result of a misunderstanding," police said.
A Ryanair spokesman told the BBC the evacuation in Oslo was due to a "hoax security alert".
The aviation industry responded quickly to Norway's helicopter crash, which left all 13 passengers on board presumed dead.
The UK Civil Aviation Authority said all UK commercial passenger flights using the Airbus EC225LP helicopter have been grounded.
Meanwhile, the Norwegian Civil Aviation Authority has said it has recovered the crashed helicopter's flight recorders.
Work has already begun on removing the wreckage, as Norwegian authorities begin their investigation to uncover the causes of the accident.
ITV News Correspondent Juliet Bremner reports:
The Norwegian Civil Aviation Authority has said it has recovered the crashed helicopter's flight recorders.
Spokeswoman Hege Aalstad confirmed the black boxes had been found but did not give any further details.
The flight data recorder and the cockpit voice recorder could help explain the causes of the crash.
The statement comes after the UK Civil Aviation Authority announced that all UK commercial passenger flights using the Airbus EC225LP helicopter are grounded as of 9pm on Friday.
Norway's prime minister Erna Solberg posted a message on Twitter describing the Norwegian helicopter disaster as "horrifying".
All 13 people on board the aircraft are presumed dead, according to Norwegian police.
The British Airline Pilots Association (BALPA) has said the thoughts and prayers of all British pilots are with those affected by the helicopter crash in Norway.
The ripples of this accident will spread way beyond Norway; a country with a good safety record.
The worldwide helicopter pilot community is united in demanding that we get to the bottom of what caused this latest accident in the North Sea and what can be learned from it.
There are global standards on the undertaking of accident investigations. They have proved the bedrock of how we learn from each tragic event and aim to make flying even more safe. BALPA subscribes to those standards and will do all that is needed to help in this most recent incident.
The UK Civil Aviation Authority has said it has suspended flights of Super Puma helicopters of the same type that crashed off the coast of Norway.
Following the accident, the UK CAA has issued an instruction to stop any commercial passenger flights by UK operators flying the Airbus EC225LP helicopter.
This mirrors action taken by the Norwegian CAA. The restriction does not apply to search and rescue flights.
The accident involved a Norwegian helicopter and will therefore be investigated by the Norwegian authorities. We will offer any assistance that we can.
We remain in close contact with all UK offshore helicopter operators to continue to assess the situation.
The authority added that its thoughts are with those affected by the accident.
The Airbus Super Puma helicopter that crashed off Norway's coast had maintenance servicing delayed twice in 2015, a Norwegian Civil Aviation Authority official told local media.
Hege Aalstad, a senior legal adviser at the authority, said: "I can confirm that this specific helicopter had seen its maintenance delayed. It is correct that there was an application for a so-called travel-time extension.
"The first one was for a delay of 100 flying hours ... and the other was also for 100 flying hours."
The aviation authority also said that it has imposed a flying ban on the helicopter type involved the crash
All 13 passengers on board the helicopter that crashed near the city Bergen are presumed dead, according to Norwegian police. One British and one Italian national are among the casualties.
The Rescue Coordination Centre said search and rescue operations have been called off.
A British national has died in a helicopter crash in Norway, the Foreign and Commonwealth Office said.
The statement comes as local police told Norwegian media that all passengers that were on board the helicopter that crashed off Norway's coast are presumed dead.
The Rescue Coordination Centre said rescuers are ending operations.
All 13 passengers on board the helicopter that crashed off the west coast of Norway are presumed dead, local police told a Norwegian daily newspaper.
Emergency services have found 11 bodies but the search for the remaining two passengers is ongoing, a spokesman from the Rescue Coordination Centre for Southern Norway confirmed.
One British and one Italian national were among 13 passengers on board the Eurocopter model that crashed on Friday on its way to shore from Statoil's Gullfaks B platform in the North Sea. The other passengers were Norwegian.
The Norwegian Civil Aviation Authority said it has imposed a flying ban on the helicopter type involved the crash.
The authority said in a statement: "There have been challenges with this kind of helicopter model in 2012, when errors in the main gear box were identified. That model received flying restrictions in 2012 and 2013."
Several people have been found dead following a helicopter crash off the coast of Norway, local media said on Friday.
Earlier police reported that no survivors have so far been found during its large-scale search.
Some 13 people were on board the helicopter, which was on its way to shore from Statoil's Gullfaks B platform in the North Sea.
"We have not found any survivors. We are still looking", a police spokesperson said. "We are searching a large ocean area".
A spokesperson for rescue co-ordination said the helicopter was "completely destroyed".