David Cameron was called on last night to "get a grip" on leading Conservatives using references to Nazism to attack their political opponents.

The call from Labour came after Daniel Hannan, a Tory MEP, caused uproar in the European Parliament yesterday when he linked Hans-Gert Poettering, its German President, with Adolf Hitler.

Mr Poettering was about to be given extra powers by MEPs to curb disruptions in the chamber which began last week when UK Independence Party MEPs and some Conservatives pressed for roll-call votes on every issue.

Mr Hannan, MEP for South East England, told the chamber that only his personal respect for Mr Poettering prevented him from comparing a European Parliament move to tighten procedural rules with Hitler's Nazi law of 1933 which suspended parts of the German constitution and gave Hitler total power.

Martin Schulz, the German Socialist leader, condemned Mr Hannan, saying: "People like Hannan are not only not speaking on behalf of Conservatives in Europe, they have no home in the European Parliament. They are entirely isolated. David Cameron should reflect on whether such people so close to right-wing extremists have a place in his party."

Last night Mr Hannan apologised to Mr Poettering but insisted he had never used the "H word". He said: "I do not compare anyone to Nazis.

"I would certainly make no such comparison with Hans-Gert Poettering who, as I have always acknowledged, has an honourable record of opposition to totalitarianism, and who tragically lost his own father in the war. I am sorry if I hurt his feelings."

At Westminster, Jim Murphy, the UK's Europe Minister, said: "This is the third time in recent days a high-profile Tory politician has used Nazism as a political insult. It's time for David Cameron to get a grip on this.

"We can all have different views but to call someone a Nazi is tasteless. Nazism was a unique evil in human history. To use it as a term of parliamentary debate demeans the memory of those who suffered," he added.

Giles Chichester, the Conservative leader in the European Parliament, said he would be deciding later today what action, if any, he would take over Mr Hannan's remarks.

Later, Mr Hannan called for an "amicable divorce" between UK Tory MEPs and their continental centre-right colleagues in the European Parliament's EPP group.

He claimed "in plain violation of their own rules of procedure" parliamentary chiefs had been given the right arbitrarily to set aside Brussels established rules.

The Tory MEP added: "An electoral majority, I said, could not over-rule a constitution. Majority or no, the Parliament still had to follow its own rule book. To do otherwise would be to replace the rule of law with arbitrary government.

"The 1933 Enabling Act had had a technical majority in the Reichstag but it opened the door to unconstitutional rule."

He added: "Whatever else MEPs are, they are not Nazis: many of them have proud records of fighting totalitarianism throughout the world. That is why it was so disappointing to see them resorting to this appalling measure in order to silence dissent."