* Stick-wielding individuals dispersed protesters -witnesses
* Some 30 demonstrators called for resignation of president
LUANDA, March 12 (Reuters) - Angolan police are investigating a weekend clash in the capital Luanda between young anti-government protesters calling for the resignation of President Jose Eduardo dos Santos and pro-government supporters who confronted them.
Witnesses said at least three protesters were injured when individuals dressed in plain clothes, some armed with sticks, moved in to disperse the small demonstration on Saturday by about 30 young people in the poor suburb of Cazenga.
The demonstrators called for Dos Santos to quit. They also called for the removal of Susana Ingles, whose re-appointment as the head of Angola's national elections committee in January has raised political tensions ahead of an election later this year in sub-Saharan Africa's second biggest oil producer.
"The National Police received complaints that two different groups were confronting each other in Cazenga and it is presumed the groups had different philosophies," a police spokesman said, quoted by the Portuguese news agency Lusa late on Sunday.
"Some support the democratically-elected state institutions and others contest the authorities," he added, saying that the police, who arrived at the scene after the clash ended, would continue investigating the incident.
Several protests were attempted last year by a budding anti-government youth movement in Angola, presenting a rare challenge to the 32-year rule of Dos Santos. Most of the protests were blocked by police and one resulted in several arrests and injuries to protesters, journalists and police officers.
Opponents of the government say national elections committee chief Ingles is linked to Dos Santos' ruling MPLA party and so cannot guarantee a free and fair vote in parliamentary elections to be held in the third quarter of this year.
The parliamentary election will be only the second in Angola since the end of a 27-year civil war in 2002, and will elect the country's president as well as lawmakers.
The MPLA has defended Ingles' re-appointment saying it was an impartial decision by the Magistrates Superior Council and that opposition parties' criticism has been aimed at causing instability in the run up to the election.
The main opposition party UNITA has threatened to organise its own protests if further appeals and talks with the ruling party about the issue are not satisfactory.
Human rights organisations have long accused Dos Santos' government of avoiding public scrutiny, repressing protest and dissent and mismanaging the country's oil revenues.
At the Cazenga protest on Saturday, the demonstrators shouted "Violence no, freedom yes!" and carried banners saying "Susana (Ingles), get out of the CNE (national elections committee)". They dispersed after an unidentified person fired a shot in the air.
Earlier, some 15 unidentified individuals in plain clothes, some wielding sticks, had moved to break up the demonstration. They appeared well organised and commanded by one of their number, witnesses said. At least one protester was caried away by colleagues with his face bloodied.
Lusa said a senior member of the Bloco Democratico opposition party had also suffered injuries at the protest and was later assaulted by unidentified men outside a clinic in Luanda. The agency said police declined to comment on this.
Opposition parties argue Ingles' re-appointment violates election laws because they say she does not fit the legal requirements to head the committee as she is a lawyer and not a magistrate court judge.
The opposition walked out of her inauguration ceremony last month and boycotted a vote on the final two parts of the reformed electoral law, approved by the MPLA in February.
The ruling MPLA, which won the civil war against UNITA, obtained 82 percent of the vote in an election four years ago and is widely expected to win the 2012 vote.
(Reporting by Shrikesh Laxmidas; Editing by Pascal Fletcher and Angus MacSwan)