A Home Office roundup of suspected illegal immigrants was condemned on Friday by the Ukip leader Nigel Farage as deeply disturbing, as Labour called on the home secretary to reveal whether the sweep had broken official guidelines on how to conduct stop and search operations.

The Equality and Human Rights Commission (EHRC) also said it was investigating the incident.

The sweep by the UK Border Agency, mainly at rail stations, has caused a furore, partly because the Home Office issued press releases and Twitter updates saying how many "immigration offenders" had been arrested, apparently prejudging their guilt.

The Twitter updates followed the Home Office use of vans warning illegal immigrants that they must "go home" or face arrest.

Farage said: "Spot checks and being demanded to show your papers by officialdom are not the British way of doing things. Yes, of course we want to deal with illegal immigration, but what's the point of rounding people up at railway stations if at the same time they're still flooding in through Dover and the other nearly hundred ports in this country.

"I'm astonished that the Home Office has become so politicised that they're actually advertising 'another 10 arrested'. Before long they'll be live video-streaming these arrests. I don't like it. It really is not the way we've ever behaved or operated as a country. We don't have ID cards; we should not be stopped by officialdom and have to prove who we are."

He said the solution lay in proper checks at the borders.

Chris Bryant, the shadow home office minister said it was wrong to arrest people on the basis of racial profiling. He asked the Home Office to disclose whether the sweep was based on specific intelligence and reasonable suspicion, as required in Home Office guidelines.

Bryant said: "It is in everyone's interest to combat illegal immigration but profiling is not acceptable and should not be happening under any circumstances. Operations need to be intelligence-led not based on ethnicity."

There had been protests at railway stations from commuters that the UKBA was targeting people from ethnic minorities.

Mark Harper, the home office minister, defended the operations, saying the police had legitimate powers to search and arrest so long as it was based on intelligence and reasonable suspicion that they were offenders.

"I'm confident we have robust rules to make sure we're not discriminating against people under the law. I'm confident we'll be able to show to the EHRC's satisfaction that we haven't been discriminating."

Anti-racism campaigner Doreen Lawrence has questioned the apparent focus on non-white people in the operations being carried out in and around train stations. The mother of the murdered teenager Stephen Lawrence told ITV1's Daybreak programme on Friday: "I'm sure there are illegal immigrants from all countries, but why would you focus on people of colour? … I think racial profiling is coming into it."

Asked if the spot checks were a cause for her to take up in her new role in the House of Lords, she replied: "Definitely so."