JOHANNESBURG (Reuters) - South Africa's ruling ANC kicked out its firebrand Youth League leader, Julius Malema, from the party for five years on Thursday after finding him guilty of dividing and bringing the 99-year-old liberation movement into disrepute.

The decision to send him into the political wilderness dealt a major blow to the career of Malema, whose push to nationalize mines in the world's biggest platinum producer has unnerved investors.

Derek Hanekom, head of the African National Congress disciplinary panel, said Malema had been found guilty of causing divisions in the party.

Ill-discipline is not a cure for frustration, Hanekom told a news conference, with committee members saying it was one of the harshest punishments handed down to a party member.

(His) careless, negligent or reckless pronouncements and utterances were a deviation of established and ongoing ANC policy and had the effect of embarrassing and bringing the organization into disrepute within and beyond the borders of South Africa, Hanekom said.

South African stocks extended gains after news of the suspension of Malema, 30. The rand also firmed slightly after the announcement.

Malema told a rally in his home base to the north of Johannesburg that he would appeal the decision.

Moses Ramafhafi, a student present when Malema addressed the crowd at a university campus in Polokwane, 320 km (200 miles) north of Johannesburg, said Malema appeared upbeat.   

He said he is aware of the verdict and will appeal, Ramafhafi told Reuters. He thanked ANC youth supporters, saying he will fight to the end and he will win.

The ANC has a solitary body to hear the appeal and Malema will stay in office until it reaches its decision. If the body, staffed with many senior ANC members who have been critical of Malema, upholds the verdict, the youth leader must step down.

He can then try to have the ANC's National Executive Committee review the case. But the body headed by his foe, President Jacob Zuma, is unlikely to reinstate Malema.

'HUGE MISCALCULATION'

The principles enunciated are so watertight that it's going to be difficult to appeal. The principles enunciated take us back to the ANC of Nelson Mandela ... and that is where Julius Malema and his Youth League made a huge miscalculation, political commentator Justice Malala said on news channel eNews.

The suspension of Malema should help pave the way for Zuma to secure a second term as ANC leader -- and hence the country's president -- at a party conference in a year.

His suspension should also silence, at least for now, calls to take over mines, a move analysts said would bankrupt Africa's largest economy.

But Zuma is not assured of re-election as ANC head. Many in the party say his leadership has been ineffective and that he has done little to improve the lives of the country's poor black majority, who formed Malema's support base.

Unemployment is officially around 25 percent. Millions still live in squalid shack settlements clustered around big cities. Youth unemployment is about 50 percent, and a recent study by the South African Institute of Race Relations said about half of people now aged 25-34 would never find work.  

Whatever they do with Malema the big issues he has raised and what he represents won't go away. The poverty, the inequalities and the unemployment continue, said Christie Viljoen, an economist, at NKC independent economist

He's not necessarily going to lie down. He's going to continue being vocal and somebody else will probably step up to take his place at the Youth League, Viljoen said.

ANC insiders say Malema is part of a plot to replace Zuma with a leader more sympathetic to the Youth League's push to nationalize the mines and seize white-owned farms for redistribution to impoverished blacks.

Malema was writing a university exam at the time of the decision and the decision did little to alter the views of his legions of supporters who admire him for his rags-to-riches life and envision him as a future leader.

One Malema supporter said in a tweet: You can silence the commander-in-chief of the revolution but you can never kill the revolution! Long live President Malema.

(Additional reporting by Ed Cropley, Mmathabo Tladi and Peroshni Govender)