|Julius Malema played a pivotal role in Jacob Zuma's rise to power as president [Al Jazeera]
South African police have fired rubber bullets and tear gas to disperse supporters of the leader of the youth wing of the governing African National Congress (ANC) in Johannesburg.
Julius Malema was due to face a disciplinary hearing on Tuesday when hundreds of his supporters started to throw stones and bottles at police.
Malema, 30, is accused of "sowing divisions" in the party and bringing it into disrepute by calling for the overthrow of Botswana's government.
Correspondents from the AFP news agency at the scene said Malema's supporters burnt the ANC's flag and T-shirts bearing the face of Jacob Zuma, the South African president.
The controversial firebrand leader is being charged along with five other youth league officials.
He was put on probation by the party's disciplinary committee last year after pleading guilty to public criticism of Zuma.
Supporters of Malema, who could be expelled from the party at the closed-door hearing, had camped overnight outside the ANC headquarters in central Johannesburg.
"We are here to support our hero. Malema speaks for us. If he is being charged, then charge all of us," said Thabang Mokoena, 29, one of the supporters who arrived by bus from Malema's home town in Limpopo province, which borders Zimbabwe.
Police erected razorwire barricades around the ANC building while a police helicopter hovered overhead, a a Reuters journalist said.
At least one police officer was wounded after being hit with a brick, a police spokesman said.
South Africa's eNEWS channels said one of its television crews was also attacked.
The protesters were trying to break through the police barricades towards the building where the hearing was due to have started at 0800 GMT on Tuesday.
They waved placards saying: "Hands off Julius Malema" and one reading: "We are prepared to take arms and kill for Malema".
Fallout with Zuma
Malema, who has called on his supporters to behave, was a key ally in Zuma's rise to power.
However, he has since fallen out with the president, who came to office in 2009 and is struggling to consolidate his support in the ANC ahead of the party's elective conference next year.
Zuma is hoping to be re-elected as the ANC leader which will allow him to stand for a second term as president in elections in 2014.
But many of the "Young Lions", as the youth wing is called, would rather see Zuma replaced as party leader with Kgalema Motlanthe, his deputy.
That change would almost certainly see Motlanthe becoming South Africa's next president.
Malema is accused of calling last month for a change of administration in neighbouring Botswana, which he said had a "puppet government" that was "in full co-operation with imperialists".
He later apologised for the remarks after a public rebuke from the ANC leadership.
Nationalisation of mines
Malema has become one of South Africa's most controversial figures since being elected president of the youth league in 2008.
He has called for nationalisation of the country's mines and redistribution of wealth to impoverished blacks, a move that has struck a chord with millions of black youth, who face a 25 per cent unemployment rate.
Al Jazeera's Jonah Hull said: "Malema has so far held his position despite a lavish lifestyle and fiery racist rhetoric that have embarrassed the ANC, in particular his insistence on singing a so-called revolutionary anthem at public rallies calling for death to white farmers.
"Crucially for South Africa's economy, international investors are also watching closely, nervous of Malema’s populist calls to nationalise the mining industry.
"If he survives this week’s disciplinary hearing, those calls will only grow louder."