RIO DE JANEIRO, May 17 (Reuters) - Brazil's Petrobras has dismissed 20 employees who worked closely with former CEO Jean Paul Prates, the state-run oil firm said on Friday.

The company announced Prates' exit on Wednesday, sending its shares down. Magda Chambriard, who previously led oil and gas regulator ANP and who holds views considered more closely aligned with those of President Luiz Inacio Lula da Silva, has been tapped by the government to take the helm of the state-run oil firm. (Reporting by Marta Nogueira; Editing by Kylie Madry)