Nigel Farage has sparked a race row after saying race discrimination laws in Britain should be dropped and firms should be able to choose who they employ.
The UKIP leader said race discrimination by employers was no longer an issue but the main concern of people was Muslim immigrants who did not want to integrate and were an "especial problem".
Speaking in an interview with the former equalities chief Trevor Phillips, Mr Farage said the worries over discrimination by employers would have been valid 40 years ago but not now.
Mr Farage, who described UKIP as "colour blind", said: "I think the situation that we now have, where an employer is not allowed to choose between a British-born person and somebody from Poland, is a ludicrous state of affairs."
"I would argue that the law does need changing, and that if an employer wishes to choose, or you can use the word 'discriminate' if you want to, but wishes to choose to employ a British-born person, they should be allowed to do so."
Mr Farage was described as "wrong and desperate for attention" by Downing Street and was accused of "breathtaking ignorance" by Labour. Nick Clegg also said he disagreed with Mr Farage's comments.
The UKIP leader fought back against critics who had attacked him for being racist and accused the media of a "wilful misinterpretation of what I said".
In tweets he said: "I'm talking Britons, whatever their heritage, being discriminated against in favour of EU migrants."
And added: "And I would suggest the REAL racists in our society are the ones who hear me say 'British' and think 'white'. Deeply concerning."
During the Channel 4 interview Mr Farage also said people were more worried there were Muslims who wanted to form a "fifth column and kill us" and that there had not previously been a group who wanted to "change who we are".
He said: "So don't be surprised if there isn't a slight increase in people's worries and concerns."
"You know, when you've got British, when you’ve got people, born and bred in Cardiff, with British passports, going out to fight for Isis, don't be surprised if there isn't an uptick in concern."
He added: "There is an especial problem with some of the people who’ve come here and who are of the Muslim religion who don’t want to become part of our culture.
"So there is no previous experience, in our history, of a migrant group that comes to Britain, that fundamentally wants to change who we are and what we are."
"That is, I think, above everything else, what people are really concerned about."
A Downing Street spokesman said: "Nigel Farage is wrong and desperate for attention. The laws are there to protect people from racial discrimination. It's deeply concerning he doesn't understand that."
Shadow UK justice secretary Sadiq Khan said: "This is one of the most shocking things I have ever heard from a mainstream politician and demonstrates breathtaking ignorance.
"We have made huge progress on tackling racial inequality and discrimination in this country, partly because of Labour's strong anti-discrimination laws, but things are still far from perfect."