Britain's former prime minister John Major called Eurosceptic party UKIP a "thoroughly negative body" which should be pushed back onto the political sidelines, during an appearance in Berlin on Thursday.

UKIP, which wants to take Britain out of the European Union, has poached two lawmakers and taken a parliamentary seat from Major's ruling Conservative party in recent months, and is expected to make more gains in May elections.

"UKIP are anti everything: they are anti-foreigner, they are anti-Europe, they're anti-establishment, they're anti-politics – I haven't found out what they are for but by goodness we know what they are against," Major said.

The prime minister from 1990 to 1997 told a meeting of Chancellor Angela Merkel's Christian Democrats (CDU) that it would be disastrous for Britain and the EU if Britons voted to leave the EU in a referendum that current Prime Minister David Cameron has promised to hold if he is re-elected next year.

Major urged EU countries to understand Britain's frustration with the EU, especially on immigration. Cameron wants to curb the free movement of workers within the bloc, in a bid to respond to widespread concerns about the number of people moving to Britain to find work.

The former prime minister said such frustrations fuelled support for hardline groups like UKIP.

"A thoroughly negative body like that is not the place into which you should put your faith, your trust and certainly not your vote," he said.

"I hope we are going to push them back to the fringes of politics from which they should never have emerged," Major added in a question-and-answer session following his speech.

The former prime minister, who was welcomed by the fervently pro-European CDU as "a very convinced European", was undermined when in office by Eurosceptic Conservatives.

(Reuters)