JOHANNESBURG (Reuters) - The South African ruling ANC's firebrand youth leader, Julius Malema, has taken a defiant stand over a rebuke by President Jacob Zuma, putting himself further at odds with the party leadership.

Malema's prominence and racially tinged rhetoric have drawn growing concern within the African National Congress as well among critics and at the weekend Zuma condemned Malema's behaviour, saying it was "alien to the ANC".

"I have not done anything to undermine the ANC," local media quoted Malema as saying on Sunday, criticising Zuma for the public rebuke and comparing him unfavourably with former President Thabo Mbeki, who was ousted by the ANC in 2008.

"Even President Thabo Mbeki, when he differed with the Youth League, and the Youth League had taken firm radical positions against him, he never did that," Malema told a news conference in the Limpopo region.

Zuma castigated Malema for throwing a foreign journalist out of a news conference, for diverging from official policy on Zimbabwe and for failing to halt inflammatory comment after the murder of white separatist Eugene Terre'blanche.

Malema has no policy-making role but has a loyal following within the ANC Youth League and among some black South Africans who feel the end of apartheid should have delivered more.