LIMA (Reuters) - Peru has demanded a “significant sum” of cash from Brazilian builder Odebrecht before starting talks toward a plea deal that would reveal the names of officials it bribed over a period spanning three presidencies, the attorney general’s office said Monday.

A general view of the headquarters of Odebrecht, a large private Brazilian construction firm, in Lima, Peru, February 24, 2016. REUTERS/Janine Costa

Hamilton Castro, lead prosecutor investigating the company, declined to specify how much Peru was seeking initially, but said Odebrecht would have to pay a bigger sum later in a final agreement after it provides details on crimes it committed in Peru.

Last month Odebrecht, a family-owned conglomerate at the center of Brazil’s biggest ever graft scandal, signed a plea deal in the United States. It acknowledged distributing hundreds of millions in bribes across Latin America, including $29 million in Peru from which it got more than $143 million in benefits.

“The illegal earnings the company obtained must be returned to the Peruvian state, that’s why we’re negotiating a significant sum of cash that must be deposited in public coffers as prepayment,” Castro told a news conference, describing the requirement as “unprecedented” in the Andean country.

Castro said his team would uncover Odebrecht’s kickback schemes in Peru with or without its help, but that direct talks would expedite the investigation he started in November based on Swiss intelligence reports.

Odebrecht said in a statement that it would cooperate with prosecutors and was carrying out internal reforms to prevent corruption. The company declined further comment.

A plea deal with Peru would be the second outside Brazil for the company, which faces mounting debt, financing troubles and criminal probes from Ecuador to Panama.

Odebrecht and an affiliated company agreed to pay a record $3.5 billion in a settlement last month with U.S., Brazilian and Swiss authorities.

Odebrecht operated a sophisticated network of corruption and had encrypted details on its bribes that Swiss prosecutors were still working on decoding, said Castro.

Castro said Peruvian prosecutors had made several trips abroad and established strong ties with their foreign counterparts that were yielding important results.

“We’ve already secured the fundamental information” Castro said.

Peru was the first country outside Brazil where Odebrecht ventured nearly four decades ago, and is home to some of its most ambitious projects, from an irrigation tunnel through the Andes to a highway that crosses the Amazon.

Last week the government of President Pedro Pablo Kuczynski said Odebrecht would be barred from bidding on public contracts thanks to new anti-graft rules and that it might sue the company for damages.