At least one of the businessmen accused in an investigation of widespread corruption in Argentina has admitted that he paid government officials money for "electoral campaigns" in exchange for the awarding of public works contracts.

The case is based on an investigation by the Argentine newspaper La Nacion into alleged corruption over more than a decade during the governments of former President Cristina Fernandez and her late husband and predecessor, Nestor Kirchner.

Some have compared it to "Operation Car Wash," the widespread corruption probe that has shaken Brazil's elite by uncovering billions of dollars in bribes and kickbacks and that has resulted in the jailing of many of its most powerful business leaders and former President Luiz Inacio Lula da Silva.

Last week, authorities in Argentina carried out raids and arrested at least a dozen businessmen and former government officials, while a local judge called on Fernandez to testify Aug. 13.

Fernandez is currently a senator, a post that grants her immunity from prosecution. She has not spoken publicly since the scandal broke out.

In plea-bargain testimony, Juan Carlos de Goycoechea, a former head of the Argentina branch of Spanish construction company Isolux Corsan, said he was forced to pay officials in Fernandez's 2007-2015 administration in order to get government contracts. But he said he did not consider them to be bribes. Goycoechea's lawyer said Monday that the payments were for political campaigns.

The investigation by La Nacion said the driver of one of the accused kept eight notebooks in which he wrote down detailed information on the alleged hauling of $160 million in bags of cash during 2005-2015. Fernandez's private address and the presidential residence are allegedly mentioned.

Some judicial experts say there is a lack of real evidence in the case since the investigation is solely based on photocopies of notebooks. But the investigating prosecutor has said the information in the notebooks has been corroborated with other evidence.

Fernandez faces several other court actions in separate cases involving alleged money laundering, possible illegal enrichment and fraud. She has denied wrongdoing in those cases.

Argentine media also reported Monday that one of President Mauricio Macri's cousins, Angelo Calcaterra, is among those being investigated and that he has provided plea-bargain testimony.

Fernandez and Kirchner were Argentina's most dominant political leaders in recent decades and are often credited with lifting the country out of its worst economic crisis in 2001. Detractors, however, say their social policies contributed to one of the world's highest inflation rates and criticize the couple's personal enrichment and their ties to scandals.

Fernandez has always dismissed the accusations as lies by the press or defamations by enemies aimed at discrediting the achievements of their collective 12 years in power.