Election 2015: Farage 'used tone to get noticed'
UKIP leader Nigel Farage has admitted the tone he has used on issues including immigration and HIV was designed to "get noticed".
In an interview with Evan Davis, Mr Farage said his party was offering "positive" solutions on immigration.
But he said people in the UK should be concerned about "those within that wish to fight us".
He also told the Newsnight presenter he had been overworked at the start of the campaign, but had adjusted his diary.
The interview will be aired on Wednesday at 19:30 BST on BBC One.
It is part of a series of interviews with the main party leaders.
Mr Farage was asked about comments he made on US TV about immigration and ghettos in the UK following the Charlie Hebdo attacks in France.
He said: "What I've said about the UK is that uncontrolled mass immigration has led to increasing division and ghettoisation in our towns and cities."
The UKIP leader said "you could argue" there are parts of the country where the police have withdrawn and Sharia law applied.
And he said turning a blind eye to such issues had led to "some of the most appalling sexual scandals that I think we've seen in our history".
Mr Farage discussed immigration at length and denied criticising Muslims.
He admitted being happier with immigration from India and Australia than "from countries that haven't fully recovered from being behind the iron curtain".
On the tone of his comments, he said: "To wake people up to the truth of what is going on you sometimes have to say things in a way to get noticed."
But he said his party had a vision for how to tackle immigration.
Analysis: Robin Brant, political correspondent
He does plenty of interviews and he's got two televised debates under his belt, but this was probably the toughest exchange so far.
During a half hour of intense scrutiny Nigel Farage was at times tetchy, even angry. "I'm not having this," he said, when he accused his interrogator of misquoting him. "I don't hate anything" he said when he thought words were being put in his mouth. "I couldn't care less," he said - twice - when pushed on one sensitive issue. He was combative and he stood his ground.
But the interview did emphasise one thing - numbers are not his strong point. On UKIP's plan for big tax cuts and deficit reduction he was nonchalant in saying "dynamic growth" in the economy - more revenue from less tax - was the secret to it working.
It's a reminder that although the party has a comprehensive manifesto on offer, that's not what UKIP is really about. And that's not what some people find appealing about it, which is why he can afford to be nonchalant.
He added: "The argument we are now making is that we are the one party that firstly offers a solution, which is to take back control of our borders, and secondly has a positive and an ethical vision for how immigration should be managed by having an Australian-style points system."
The MEP said he was only talking about a "mercifully small percentage of the Muslim population" in previous comments.
And pointing to estimates hundreds of Britons have gone to fight in Syria, he said: "Should we concerned about it? Yes of course we should."
The UKIP leader also said his party's potential was "massive" if they did well on 7 May.
The three areas it will be judged on are the number of MPs elected, the number of seats where it comes second and its share of the overall vote nationwide, he added.
Mr Farage insisted he did not regret saying he would stand down as party leader if he fails to win election in Thanet South on 7 May.
He said: "I believe that I have given everything to try and make UKIP a political success. But I have to get over the particular Becher's Brook. I am confident and I believe I will."
The MEP also admitted he was not operating at "100%" at the start of the election campaign.
He said: "I wasn't feeling quite as sharp and as fit as I should have been. I think that's because frankly in my enthusiasm for UKIP to succeed in this election I got my diary planning wrong and I was doing way way too much."
But he added: "I've readjusted that - I have to say the last two or three days I'm feeling pretty bouncy."