Julius Malema supporters clash with South Africa police
South African police have fired stun grenades at supporters of controversial ANC Youth League leader Julius Malema ahead of his disciplinary hearing.
Mr Malema, 30, is accused of "sowing divisions" in the party and bringing it into disrepute by calling for a change of government in neighbouring Botswana.
Once a close ally of President Jacob Zuma, the populist Mr Malema has become a fierce critic.
His supporters threw stones at police who were blocking them in Johannesburg.
The police erected a steel gate and barbed wire to close the main street leading to Luthuli House, the African National Congress headquarters where the hearing was held.
Thousands of Mr Malema's supporters remained outside for much of the day, chanting and setting rubbish on fire.
Some set on fire a T-shirt emblazoned with President Zuma's face, while other shouted "Zuma must go".
The ANC later said the hearing would be moved to a secret location outside the city to reduce disruption, while Mr Malema urged his supporters to show restraint.
One police officer and several journalists were injured in the clashes.
Mr Malema, who is charged along with five other top youth league officials, could be expelled from the ANC at the closed-door hearing.
He was put on probation by the disciplinary committee last year after being found guilty of criticising Mr Zuma.
Mr Malema, under separate investigation for alleged fraud and corruption, says he will accept the committee's ruling.
"We are taking responsibility for our actions and we are prepared for anything. We have always maintained that the ANC is our future, if that future is expulsion so be it," he said on the eve of the hearing.
Correspondents say the youth league leader's calls to nationalise the mining sector and seize white-owned farm land have jarred with the party's leadership but have proved popular among his political base in impoverished black communities.
The BBC's Karen Allen described Mr Malema as a "kingmaker and political survivor", whose youth group brings the ANC a 350,000-strong block vote and influence over senior ANC leaders seeking promotion.
His disciplinary hearing sets the scene for next year's party leadership battle.
Mr Zuma's ambitions to secure a second term as ANC president could be enhanced if Mr Malema is pushed into the political wilderness, our correspondent says.
If, however, the maverick youth leader emerges with his ANC membership intact, President Zuma could face an uncertain future, she says.
The youth leader has long been a controversial figure.
He played a central role in helping Mr Zuma take control of the ANC from his predecessor Thabo Mbeki in 2007 and campaigned strongly for him in the 2009 elections, which brought Mr Zuma to power.
But on Monday, he said he did not have a personal relationship with the president, only an organisational one.
In May 2010, he was made to apologise publicly following a controversial trip to Zimbabwe where he declared the ANC's support for President Robert Mugabe at a time when Mr Zuma was mediating between the country's coalition members.
Mr Malema was also chastised by the ANC for expelling a BBC journalist from a press conference and defying party orders not to sing a racially divisive apartheid-era song, "Shoot the Boer [white farmer]".