Passengers on a Manchester-bound flight have described how two men were removed from the plane because other travellers thought they were speaking Arabic.
The plane flew on to Manchester without the men
Heath Schofield, a passenger on the flight from Malaga, described it as being a "bit like Chinese whispers".
Monarch Airlines said passengers had demanded the men were removed because they were acting suspiciously.
Birmingham MP Khalid Mahmood said it was disgraceful the pair seemed to have been judged on their skin colour.
The men - reported to be of Asian or Middle Eastern appearance - were taken from Wednesday's flight ZB 613 and questioned but were allowed to fly back to the UK later in the week.
Refusal to board
Mr Schofield, who was travelling with his wife Jo and their children, said: "We all started boarding the flight.
Heath and Jo Schofield were on the Manchester flight
"Our daughter noticed a couple of guys that were perhaps acting a bit strange. They went to the front of the queue, went to the back of the queue, and then they went and sat down by themselves.
"Anyway, we got on the plane and we boarded and it became apparent after we were already supposed to be flying that several of the passengers had refused to board the craft.
"A few rumours went round, it was a little bit like Chinese whispers, and then some more people decided they were getting off."
Plane finally took off
He said Spanish police officers came on to the plane and took the two men's passports and 20 minutes later the pair were removed from the plane.
All the passengers were then taken off and the plane and all the luggage was swept for explosives. Three hours later the passengers boarded again and the plane took off without the pair.
His wife said: "We still don't know what was said, or whether it was anything to be alarmed about."
She said: "A lot of mums were trying to calm the children down - they were getting quite panicky because of what they'd seen on the telly.
"It became apparent that the reason that some of the people didn't board the plane was because somebody had overheard the gentlemen in question speaking - I think it was Arabic."
Mr Mahmood said it was "absolutely disgraceful" that passengers had taken it on themselves to label people.
"That is not what we want. The colour of your skin shouldn't identify what you are. It is a sad state of affairs that that has happened."
He called for air passengers to understand that once people were allowed through security "they should be OK".
In a statement, Monarch said: "The captain was concerned about the security surrounding the two gentlemen on the aircraft and the decision was taken to remove them from the flight for further security checks."
David Reynolds, from the British Airline Pilots Association, said there were "very tight procedures" in place to ensure only the "right sort of people" boarded flights.
"Clearly, we can't have a situation where one passenger decides that another passenger isn't going to fly," he said.