Nick Clegg has said that David Cameron has aligned himself with “nutters, anti-Semites, people who deny climate change exists and homophobes” within the European Parliament during last night’s Leaders’ Debate.

Mr Clegg was referring to the decision last year by the Conservative leader to allign himself with right wing parties in Europe, including the Polish Law and Justice party which has been accused of homophobia, antisemitism and racism.

The party’s founder Lech Kaczynski who died in a plane crash earlier this month, was President of Poland and while Mayor of Warsaw reached international notoriety because of repeatedly banning gay pride marches from taking place in the city.

In 2007 he said: “If that kind of approach to sexual life were to be promoted on a grand scale, the human race would disappear. Imagine what grand changes would occur in mores if the traditional links between men and women were set aside.”

In the debate, Gordon Brown said that David Cameron had aligned himself to “right-wing extremists” in the European Parliament. Mr Clegg said Mr Cameron had weighed in by accusing Mr Cameron of working with “nutters, anti-Semites, people who deny climate change exists, homophobes”.

David Cameron said that both leaders had praised the party’s founder, Polish president Lech Kaczynski, when he died in a plane crash. He added: “I want to make sure that we say the same thing in Bristol about wanting to be in Europe, but not run by Europe… but not go over to Brussels and say something different.”

Mr Brown said: “These two guys remind me of my two boys at bath time – they are squabbling.”

He went on: “I am afraid David is anti-European, Nick is anti-American. Both of them are out of touch with reality.”

On Wednesday, David Cameron announced he would dispatch Nick Herbert, the most senior gay Conservative, to Poland to confront the homophobia displayed by the party’s Polish allies.