Britain's anti-EU UKIP party was dealt a blow on Saturday when senior member and MEP Amjad Bashir, left what he described as the "amateur" outfit to join David Cameron's Conservative Party.

Nigel Farage's UK Independence Party, which wants Britain to leave the European Union and immigration to be sharply curbed, responded by saying it had suspended Bashir for what it described as a string of "extremely serious" offences.

UKIP was dismissed by Cameron as "fruitcakes, loonies and closet racists" in 2006.

But the party has grown rapidly since, winning Britain's European elections in May and then poaching two of Cameron's Conservative lawmakers, making it a real threat in May's national election to all the leading parties.

With such rapid growth however it has struggled to maintain discipline and it lost several candidates in recent months including one who was recorded making insulting remarks about gays and Chinese people.

On Saturday Bashir, a member of the European Parliament and one of UKIP's few senior politicians from an ethnic minority, told the Telegraph newspaper he had applied to join the Conservatives because UKIP lacked policies.

He said the Conservative Party was the only one that could control immigration or give Britons a say on whether they want to remain within the European Union.

"On Friday I met David Cameron and applied to join the Conservative Party," he told the newspaper. "It is clear UKIP's action today is a desperate attempt to spoil this and is without any foundation.

"I've seen UKIP both at home and abroad and I'm sorry to say they're pretty amateur".

UKIP said in a statement it had suspended Bashir while it carried out an investigation into issues including unanswered financial and employment questions, and interference with UKIP candidate selection processes.