A former executive of Brazil's state-run energy company told a congressional panel on Tuesday that he began accepting bribes from some of the county's top construction firms 18 years ago.

According to federal prosecutors, the scheme involved the payment of at least $800 million in bribes and other funds by big construction and engineering firms in return for inflated contracts with Petrobras. They have said that part of that money was transferred to the governing Workers Party and other top parties for political campaigns.

In a session broadcast live by the Globo TV network, Pedro Barusco told lawmakers that as part of a plea bargain deal with prosecutors, he has agreed to repatriate some $100 million he deposited in bank accounts overseas.

Barusco, the first witness to be questioned by the panel, said he and other company executives took the initiative to approach the companies for bribes in 1997.

But by 2003, "that practice had become more widespread and institutionalized," he added.

He said the ruling Worker's Party received twice as much as he did in illegal payments, "which makes me estimate that between $150 million and $200 million went to the Workers' Party."

Last week, the Supreme Court ruled that 54 top politicians be investigated for alleged ties to the kickback scheme.

Under Brazilian law, the Supreme Court has to approve any investigation of legislators or top officials in the executive branch. Any criminal charges or trials of such figures must also must be approved and judged by the top court.

Black market money dealers who struck plea bargain deals with prosecutors have said they helped move the money around along with former top Petrobras executives who acknowledged raking in hundreds of millions in bribes.

Among those to be investigated are former president and current senator Fernando Collor, who was forced from the presidency by a corruption scandal in 1992.

Also to be investigated are Senate leader Renan Calheiros and Eduardo Cunha, who heads the lower house. Both are members of the powerful Brazilian Democratic Movement Party, part of the governing coalition.