UKBA officers targeted Walthamstow in an operation this week which some claim was carried out on the basis of people's appearance

The Government’s Immigration Minister Mark Harper said the operations during the week were intelligence-led and that those stopped were chosen on the basis of their behaviour, not their ethnicity.

An investigation has been launched by the Equality and Human Rights Commission to determine whether the spot-searches were based on appearance and therefore discriminatory.

The minister told the BBC Radio 4 Today programme that UKBA officers are not allowed to question people based on their appearance, but rather officers use behaviour as a measure of whether they will question a person.

He said: “The operations carried out at two Tube stations were based on specific intelligence about concerns that we had about those particular locations and about the times when we conducted the operations.

“We weren't stopping people based on their race or their ethnicity.

“We were only stopping people and questioning them where we had a reasonable suspicion that they were an immigration offender.”

The Guardian had approached UKBA for information revealing the number of people stopped on Thursday and the ethnic breakdown of the searches but reports suggest no details of this kind were recorded.

Operations at Walthamstow Central on Thursday saw officials arrest 14 people for immigration offences.

Those arrested were from Pakistan, India, Nigeria and Ghana and will be considered for removal from the UK.