Sao Paulo, Jan 27 (IANS): Three police officers in Brazil are under investigation after a protester was shot during an anti-World Cup protest in Sao Paulo.

Fabricio Proteus Nunes Fonseca Mendonca Chaves, 22, is in a serious condition at the Santa Casa hospital's intensive care unit with bullet wounds in the neck and groin, reports Xinhua.

Sao Paulo's public defender's office Sunday requested an immediate probe by the state's security secretariat (SSP) and the internal affairs department of the military police.

"According to what I have been told, the police acted with absolute excess, disproportionate to the situation," said Carlos Weis, a human rights spokesman for public defender's office.

"It's important to put into context that the young man had participated in the demonstration," he said.

According to a SSP statement, Chaves was found to be carrying an "explosive object" after being stopped and searched by the officers.

He then tried to run away before producing a knife from his pocket.

"At that moment the police shot at the suspect, who fell to the ground, then rose in an effort to escape again before collapsing," the statement said.

Meanwhile, more than 100 people arrested during Saturday's protest in Sao Paulo were released from police custody Sunday.

The rally, which drew an estimated 2,500 participants, turned violent when a group of masked attackers clashed with police.

Others vandalised banks and shops while a private vehicle was torched.

It was one of a series of anti-World Cup protests planned by activist group Anonymous, continuing nationwide rallies that began during the Confederations Cup last June.