Former Brazilian President Luiz Inácio Lula da Silva has testified to the authorities in the investigation by Operation Zealots on bribery allegations during his term, which also involved his son.

Correio do Estado said Lula's testimony to the Federal Police started on Wednesday at 2:30 p.m. in relation to the bribery payments allegedly made for the approval of three measures in tax benefits to the automotive industry.

Two of these measures were reportedly under Lula's leadership from 2003 to 2011.

It added that the company of Lula's son, Claudio Luis, received $2.4 million from the office of R & Marcondes Mautoni and other companies from the automotive sector.

Lula, who came with his legal counsel, Cristiano Zanin Martins, claimed that the approval of the measures "met the interests of states such as Bahia, Pernambuco and Goias," and that the governors exerted effort to have them approved.

It was also noted in the Correio do Estado report that the former president's testimony was supposed to take place last month, but his lawyer asked to have it postponed until January because of the recess period of the parliamentary.

According to Pulse, Lula was earlier summoned to testify in the bribery claim, which reportedly favored businesses.

He was called along with other current officials, like Deputy Finance Minister Dyogo de Oliveira, after the defense of detained lobbyist Alexander Paes dos Santos requested for their testimony.

The same report also claimed that Lula was previously invited for questioning in the same investigation, locally termed as "Operacao Zelotes" (Operation Zealots).

Insight Crime explained that Operation Zealots started in 2014 and investigated tax-fraud cases which totaled to about $5 billion.

The former Brazilian president is reportedly not directly implicated in the bribery cases, but his image has already been affected by the involvement of his son.

Aside from this investigation, Lula's name was also dragged into the kickback and bribery scandal at the state-run oil company Petrobras. The investigation of the contract-fixing allegations at the state-run multinational energy corporation involved 21 companies and 59 high-ranking officials who are believed to have been involved in an estimated $9 billion worth of contracts.

An Associated Press report published by Huffington Post said the probe was launched after similar investigations into the alleged kickbacks and bribes at the energy corporation took place. 

Once found liable for the contract-fixing charges, the same report said that companies will not be included in public biddings.

The scheme reportedly started in 1998, but only went full swing under the Da Silva's term in 2003.