BRASILIA, April 11 (Reuters) - A Brazilian judge has suspended the chair of state oil firm Petrobras' board, Pietro Sampaio Mendes, over a conflict of interest regarding his role in the Ministry of Energy, according to a court decision seen by Reuters on Thursday.

The company did not immediately respond to a request for comment on the ruling, ordered by Sao Paulo Judge Paulo Cezar Neves Junior, who also ordered payments to Mendes be halted.

Petrobras shareholders had appointed Mendes to the post last year.

The firm's previous board - chosen by the administration of right-wing former President Jair Bolsonaro alongside an internal committee - had initially ruled that Mendes and three other members of the incoming board were not suitable.

They had argued that Mendes' election would present a potential conflict of interest, as he also serves as oil and gas secretary at Brazil's Mines and Energy Ministry. Shareholders however went on to approve the nominations. (Reporting by Ricardo Brito and Pedro Fonseca; Editing by Valentine Hilaire, Christopher Cushing and Lincoln Feast.)