By Anthony Boadle and Leonardo Goy BRASILIA (Reuters) - Leftist former leader Luiz Inacio Lula da Silva was sworn in as President Dilma Rousseff's chief of staff on Thursday amid a deepening crisis in Brazil as protests against his appointment continued for a second day and a judge sought to block the move. Police used tear gas to disperse hundreds of opposition protesters who clashed with Lula's supporters outside the futuristic presidential palace in the capital Brasilia before his swearing-in. Demonstrations also took place in Sao Paulo and Rio de Janeiro amid anger that Lula's appointment will shield the former president from prosecutors who have charged him with money laundering and fraud as part of a sweeping graft probe centered on state oil company Petrobras .