Brazil’s President Dilma Rousseff (R) greets former president Luiz Inacio Lula da Silva after Lula da Silva sworn in  as chief of staff. Reuters

Former Brazilian President Luiz Inacio Lula da Silva was sworn in as chief of staff to his successor Dilma Rousseff on Thursday.

This was  despite a judge  blocking  his appointment and Congress beginning  proceedings to impeach Rousseff in a deepening political crisis.

Police used tear gas to disperse hundreds of opposition demonstrators who clashed with Lula’s leftist supporters outside the presidential palace where he was sworn in, while ministers and corruption investigators traded barbs throughout the day.

Spontaneous protests also blocked major avenues in Sao Paulo and Rio de Janeiro, spurred by anger that Lula’s appointment will shield the former president from prosecutors who charged him with money laundering and fraud as part of a sweeping graft probe centred on state-run oil company Petrobras.

Only Brazil’s Supreme Court has jurisdiction in cases against ministers. Shortly after the swearing-in ceremony, a federal judge in Brasilia issued an injunction against Lula’s appointment on the grounds it blocked “the free exercise of justice.”

Attorney General Jose Eduardo Cardozo vowed to appeal the injunction against Lula joining the government, which he called the decision of a partisan judge.

The standoff inflamed tensions that are already running high between Brazil’s executive and judiciary branches, as the Petrobras probe reaches Rousseff’s inner circle and hangs over a congressional impeachment committee named on Thursday.