Luiz Inacio Lula da Silva has been sworn in as President Dilma Rousseff's chief of staff in Brazil, deepening a political crisis as protests against the appointment entering a second day and a judge tried to block it.

Clashes briefly erupted in the capital Brasilia after Lula - a former president - was sworn in to the role in a move that his opponents see as a ploy to shield him from prosecution.

Supporters of the left-wing leader scuffled with opponents of his Workers' Party outside the presidential palace before the ceremony on Thursday.

Police said they used pepper spray to stop fighting between the rival groups. They also moved on some 300 opposition protesters who were trying to enter the square, which was occupied by more than 300 pro-government demonstrators.

Shortly after the ceremony, a federal judge issued an injunction in an attempt to block Lula's appointment on the grounds that, by taking office, it would derail an ongoing investigation.

Al Jazeera's Margas Ortigas, reporting from Rio de Janeiro, said that the federal government headed by Rousseff would appeal against that ruling.

A defiant Rousseff, who is herself embroiled in a bribery scandal involving a state-run oil company, welcomed Lula to her cabinet.

"Convulsing Brazilian society with lies, with reprehensible practices violates constitutional rights and as well as the rights of citizens," said Rousseff, who is facing mounting pressure to quit.

With Brazil's economy mired in its worst recession in a generation, popular anger at Rousseff is mounting as the investigation - into bribes and political kickbacks at state oil company Petrobras - taints her inner circle.

The scandal has divided her governing coalition and moved her main partner, the PMDB party, closer to breaking with her government.

'Desperate gamble'

"Rousseff [is] fighting for her life," Jan Rocha, a local journalist, told Al Jazeera. "If the Congress approves the impeachment proceedings then she is gone."

Bringing Lula on board, she said, was a "desperate gamble".

"Lula is well known for his political experience and ability, and being able to persuade enough people in the Congress not to vote for impeachment," she said.

Hundreds of anti-government protesters calling for Rousseff's impeachment and Lula's arrest also blocked the Avenue Paulista in central Sao Paulo.

On Wednesday, tens of thousands of protesters thronged the streets of the Brasilia and Sao Paulo, the country's financial hub, to protest his appointment.

The clashes come a day after tens of thousands of protesters thronged the streets of the capital Brasilia and Sao Paulo [Adriano Machado/Reuters]

Source: Al Jazeera And Reuters