Nigel Farage has claimed Cologne-style mass sex attacks could happen in Britain if it stays in the European Union.
The Ukip leader told a 500 plus crowd at a pro-Brexit rally in Newport, South Wales, that German chancellor Angela Merkel had made a big mistake in lifting restrictions on Syrian refugees last summer.
Public support for asylum seekers in Germany has since dropped following allegations that hundreds of women were groped, robbed and intimated at Cologne's central station on New Year's Eve.
Speaking at the cross-party Grassroots Out event, Mr Farage said: "We've been through a hundred years of female emancipation and liberation ... and now the mistakes of Mrs Merkel are now threatening all of that.
"What we saw outside that train station in Cologne on New Year's Eve was truly and genuinely shocking.
"I am not saying that we are not immune from such problems in this country.
"But to me, if you allow the unlimited access of huge numbers of young males into the European continent who come from countries where women are at best are second class citizens, don't be surprised if scenes that we saw in Cologne don't happen more often.
"For goodness sake, do we want those young men within five years to have EU passports and to be able to come to our country and to reverse a hundred years of female liberation and to change our entire way of life? Surely the answer must be no.
"It is the job of the British Government to make our own laws, to control our own borders and its about time we started putting the interests of our own people first."
Dressed in a purple suit and luminous green tie, Mr Farage took to the stage in a marquee at the Rodney Parade stadium to a standing ovation before drawing laughs from the crowd after mocking pro-EU campaigners as "Remainions".
He accused Prime Minister David Cameron and Wales' First Minister Carwyn Jones of scaremongering over what would happen to the UK if it left the EU before calling George Osborne the "worst Chancellor in modern times".
Mr Farage added: "Mr Cameron has decided he decided he will fight this referendum on the issue of security. He will say that we are safer by being part of the European Union.
"I'm very sorry but the free movement of people across the Europe has meant that not only do we have the free movement of nice people but we have free movement of bad people.
"It has meant the free movement of criminal traffickers, Kalashnikov guns and terrorists.
"The most vital thing we could do protect this country against this horrendous terrorist wave that we are seeing is to take back control of our country and its borders."
The MEP insisted June's referendum would be a battle of the "political class against the ordinary decent men and women of this country".
Mr Farage also said pro-Brexit campaigners needed to reach out to all "ages, classes and ethnicities in the UK" in order to win.
The two hour event also saw speeches from journalist Simon Heffer, Labour member Simon Chilton and Conservative MP David Davies.
Mr Davies echoed Mr Farage's comments on immigration.
He said: "The vast majority of these people are not coming from Syria. They are coming from the Middle East and Africa.
"A lot of them are fit young men. If they are fleeing warfare where are their wives and mothers and sisters and why have they left them behind?"
Before the event, around two dozen protesters gathered outside the entrance to Rodney Parade holding up signs reading "no to racism, no to bigots, no to Ukip".