UKIP is to include a ban on the full veils worn by some Muslim women as part of its general election manifesto, its leader Paul Nuttall has said.
Speaking on the BBC's Andrew Marr show Mr Nuttall said wearing a burka or niqab in public was a barrier to integration and a security risk.
He also said UKIP could undertake not to stand against Brexit-supporting MPs.
Labour MP Chuka Umunna said the country would not take advice from "hate peddlers" at UKIP on integration.
The UKIP leader suggested that the party would not stand against MPs in marginal seats who supported Brexit, if local parties agreed.
He cited the example of David Nuttall, Conservative MP for Bury North, who is defending a majority of 400.
"What I don't want to see happen is good Brexiteers - not fly-by-night or five-to-midnight Brexiteers, people who've campaigned for years for Brexit - I don't want to see them lose their seats and a Remainer be there in their place," he said.
However, Mr Nuttall refused to confirm his own plans to stand as candidate in the June 8 election.
"I will make a decision in the coming week about where to stand, obviously I'll be having conversations with local branches," he said. "Nothing is decided."
In February, he failed to win in Stoke-on-Trent Central, after Labour held the seat.
Speaking about full face-veils, Mr Nuttall told the programme: "We have a heightened security risk at the moment and for CCTV to be effective you need to see people's faces.
"Secondly, there's the issue of integration. I don't believe you can integrate fully and enjoy the fruits of British society if you can't see people's faces.
"I can't walk into a bank with a balaclava on or a crash helmet, if I can't do it and other people can't do it, I don't see why there are special interests for certain people."
Muslim women who defied the ban could face a fine, he suggested.
He said that being "hidden behind the veil" contributed to 58% of Muslim women being economically inactive.
Mr Nuttall said: "We'll come in line with other European countries such as Belgium, Bulgaria - there's a ban for example in the city of Barcelona, some places in Italy and, indeed, Angela Merkel is talking about this in Germany at the moment.
"Manfred Weber, who's the leader of the biggest group in the European Parliament, is now talking about an EU-wide ban. We can either be on the curve on this or behind the curve."
Labour's Mr Umunna tweeted his opposition to the measure after the interview.
"Sorry," he wrote. "Britain won't be taking any lessons on integration from the hate peddlers at UKIP."
'Stop adding to the problem'
UKIP member and former donor, Arron Banks - who has publically called Mr Nuttall "weak" - also disagreed with the policy.
Mr Banks, who is hoping to run as a candidate for UKIP in Clacton, told the BBC's Sunday Politics Show: "I'm not personally in favour of that. I think people have a right to their religious beliefs.
"I think there are certain circumstances where if it's a security issue - maybe the airports, or public transport - it's acceptable, but I'm not in favour of curtailing people's [freedoms]."
However, he stood by the previous he call made on Twitter for a ban on Muslim immigration into the UK.
"I've said that - I'm not disputing that," added Mr Banks. "My answer is you can't possibly curtail someone's religious freedoms but what you can do is stop adding to the problem."
'No place in democracy'
Mr Nuttall also told the programme that he wanted to prevent Islamic sharia law becoming "a parallel legal system in this country".
"It cannot be right that we have court or councils in this country where the word of a woman is only worth half that of a man. That has no place in a liberal, democratic, functioning Western democracy," he said.
But he said that Beth Din, Jewish rabbinical courts, would not be affected, because they had been established for centuries and the Orthodox Jewish population was falling.
The party's manifesto is also expected to suggest that anyone with evidence of female genital mutilation taking place will be bound by law to inform police.
And it will also call for postal voting to be largely abolished, because of concerns over electoral fraud.
The former UKIP leader, Nigel Farage, proposed a burka ban in 2010.
But the party later dropped the policy, and it did not appear in its 2015 manifesto.
Full-face veils are already banned in public in some European countries, including France.