Children will have to go through full body scanners at UK airports under new proposals unveiled by the government, despite protests from civil liberty groups that the resulting images would breach child pornography laws.

Announcing the new code of conduct for scanners, the transport secretary Lord Adonis said to exclude children risked undermining the tightened security measures that were introduced after a failed attempt to blow up a plane in the US on Christmas Day.

“We will be requiring all children who are selected to be screened using the scanners. To do otherwise would risk undermining the effect of these new measures,” the code said.

“Airport security staff have all been cleared to Government security-vetting level, which includes a check of criminal and security service records. Staff have received comprehensive initial training and regular refresher training in aviation security and customer service.”

They had also been trained in aviation security and “customer service” to carry out their jobs “in a sensitive and proportionate manner.”

There were calls that the scanned images could have been ruled illegal under the 1978 Protection of Children Act.

But, the code said, that this would be outweighed by the necessity of preventing, detecting or investigating crime.

“We are aware of the possibility that some individuals, such as transgendered, disabled or elderly passengers, or passengers with particular religious or other beliefs might, notwithstanding the existing privacy controls, have concerns about undergoing a security scan.”

But, the DfT said it believed that the privacy controls were adequate.

“We believe that in such a situation the security officers have the necessary skills to be able to deal with the situation sensitively.”

But last week news emerged that a Heathrow Airport security guard was given a police warning after he was allegedly caught staring at images of a female colleague in a body scanner.

Passengers that have refused to go through the scanners have been refused boarding their plane.