Brazil's attorney general has opened an inquiry looking into allegations that former President Luiz Inacio Lula da Silva received donations for helping a Brazilian company get business in Equatorial Guinea, reports Lusa news agency.

He is already in prison serving a 12-year sentence for corruption.

In 2017, Lula was found guilty of accepting an upgrade to a beachfront flat he was buying from an engineering firm in return for help in winning contracts for Petrobras, Brazil's state oil company.

This time he is being accused of receiving bribes in return for brokering deals between Equatorial Guinea and a Brazilian construction company ARG.