Ukip's director of communications tried to haul the party's leader, Nigel Farage, off a radio interview on Friday lunchtime after he came under sustained attack over his attitudes to immigrants and his expenses.

Farage was being interviewed by one of his long-term critics on LBC when Patrick O'Flynn intervened to say the interview had run over its agreed time. The interview had lasted just over 20 minutes.

The Ukip leader was accused of "reverse-ferretting" by the interviewer, James O'Brien, over a promise to have his expenses independently audited – an offer Ukip made on the BBC's Today programme and subsequently withdrew in a Guardian interview, saying he would not be subject to a stricter audit than other MEPs.

When it was pointed out that other MEPs – including those from the Labour party – had their expenses audited O'Flynn intervened, surprising even Farage.

Asked about other MEPs' auditing arrangement, Farage said: "What they have is an auditor to make sure they spend the money in accordance with the rules. There are no expenses. There are fixed-rate allowances that I have spent in accordance with the rules."

Pressed to say if he would agree to the same audit, he said: "We will make a decision en masse. I am very suspicious of the word audit used in that context." He made no commitment to an audit of his previous allowances.

Farage was also asked why he said he felt discomfort when travelling on a train and not hearing the English language. He insisted he had not said he objected, but that he did not feel comfortable.

O'Brien asked if he objected to the fact that his wife and his children could speak German, and replied that they could also speak English, adding he "had a distinct feeling English was not the language of choice" of those people that he heard on a train. He added he did not think his wife spoke German on a train.

Farage was also challenged about his claim that there were schools in east London where a majority of pupils did not speak English," with the interviewer asserting such surveys only showed whether English was the child's first language.

O'Brien pointed out his own bilingual children would be qualified as non-English speakers on this definition. Farage agreed the definition might need reworking.

O'Brien then asked about Farage's claim that people would feel uncomfortable if a group of Romanian men moved in next door, pressing him to say whether he "would feel the same about a group of German children".

Farage replied: "I think you know the difference. We want an immigration policy that is not just based on controlling not just quantity but quality".

He added: "I am making one very simple point in this election. We cannot have any form of managed migration into Britain and remain a member of the European Union because we have an open door to nearly half a billion people.

"We would be far better off if the policy that did not discriminate against doctors from New Zealand or engineers from India in favour of anybody regardless of background and skills coming from southern and eastern Europe and that is the great debate."

Explaining his claim that Romanians were more likely to be criminals, he said: "We have a problem; unfortunately, those communist countries which I visited and I've seen the real poverty that people live in.

"We talk about exclusion in society … go and see, since the fall in communism, what has happened to the Roma communities in those countries; they don't get jobs, they've got nowhere to live and they have been forced, in many cases, to a life of crime.

"And what has happened to that open door? It has been an open invitation to the traffickers and the Metropolitan police have produced their statistics and they're eye-watering and I'm saying let's get a grip on it."

Farage accepted there were "idiots" in his party after news of more Islamophobic comments made by Ukip candidates.

"Firstly, people saying silly things; yes of course we've had more of it than we'd have liked, but what is going on in the other parties? Nobody ever does ask them? I'm perfectly happy to have a debate about our idiots and people who are offensive.

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