Anti-corruption officials are calling for Peru's three most recent ex-presidents to testify in connection with alleged bribes paid by Brazilian construction conglomerate Odebrecht for inflated contracts that authorities say cost the Andean country $283 million.

Comptroller Edgar Alarcon said at a news conference Wednesday that Odebrecht was involved in 23 public works projects since 1998 worth at least $16.9 billion. Of those, 16 have been audited and authorities detected potential irregularities, including unjustified cost overruns and forgiveness of penalties for contractual breaches that cost around $283 million.

His comments came a day after a senior anti-corruption official said she wants to take testimony from three former presidents — Alejandro Toledo, Alan Garcia and Ollanta Humala — about dodgy deals with the Brazilian builder as well as company owner Marcelo Odebrecht.

Julia Principe, the top government attorney in the Justice Ministry, said she also would like to hear from current President Pedro Pablo Kuczynski. As Toledo's prime minister in 2006, Kuczynski signed a law passed by congress allowing Odebrecht to participate in an auction to build two highways despite a ban on it bidding for government contracts at the time because it was facing legal action for irregularities in another project. Odebrecht eventually was awarded the roads contract.

Kuczynski has denied any wrongdoing and called for a "deep investigation" of Odebrecht for illicit activities in Peru.

In late December, Odebrecht and petrochemical company Braskem agreed to pay a combined penalty of at least $3.5 billion to settle allegations that they bribed government officials in a dozen countries around the world. As part of the plea agreement with the U.S. Justice Department, Odebrecht admitted to paying $29 million in bribes to Peruvian officials and has already agreed to pay back the country an initial $8.9 million for the damages it caused.

As Peruvian officials attempt to untangle the web of corruption, Attorney General Pablo Sanchez is expected to travel this week to Brazil to obtain information from prosecutors investigating Odebrecht there.

Former presidents in Peru have immunity against prosecution for crimes committed while in office.