Two women were stopped from boarding a plane at Manchester Airport after refusing to undergo a full body scan.
The passengers were due to fly to Islamabad on 19 February when they were selected at random to go through the new scanning machine.
One, who is believed to be a Muslim, refused on religious reasons and the other cited health grounds.
They are thought to be the first people to refuse to use the scanners since they became compulsory in February.
The machines were introduced as a trial at the airport in October 2009.
The women were warned they were legally required to go through the scanner, after being chosen at random, or they would not be allowed to fly, an airport spokesman said.
It is not clear whether the women were travelling together.
Security staff use the X-ray machine to check for any concealed weapons or explosives but they have been criticised as an invasion of privacy.
A Manchester Airport spokesman said: “Two female passengers who were booked to fly out of Terminal 2 refused to be scanned for medical and religious reasons.
“In accordance with the government directive on scanners, they were not permitted to fly.
“Body scanning is a big change for customers who are selected under the new rules and we are aware that privacy concerns are on our customers’ minds, which is why we have put strict procedures to reassure them that their privacy will be protected.”
The women forfeited their flight and left the airport.
In US airports where scanners are installed passengers have the option of a undergoing a body search.