BUENOS AIRES (Reuters) - The scandal that started with a former Argentine official stashing cash in a convent and deepened when records of alleged bribe payments were published took new turn on Monday with accusations by a lawyer for former President Cristina Fernandez that a dressing room in her apartment might have been contaminated by a toxic substance.

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More than a dozen construction company executives and officials from Fernandez’s administration have been arrested as result of a graft probe. The scandal threatens to damage Argentina’s already ailing economy and upset next year’s presidential election.

Investigators searched Fernandez’s Buenos Aires apartment last week, looking for evidence. On Monday she posted on her Facebook page a statement from her lawyer saying domestic employees cleaning her dressing room after the search became mysteriously ill.

“An extraordinarily grave situation arose in the residence,” the statement by lawyer Carlos Alberto Beraldi said.

He described cleaning personnel suddenly beset by “dizziness, strong itching in the throat and eyes and breathing difficulties.” It said the cleaners were treated at a hospital.

“It was found that the ailments were caused by contact with a toxic substance, and it was recommended to avoid re-exposure to the same environment,” the statement said.

“For this reason, my client decided not to return to the apartment until there is an examination of the place and the items that were subject to manipulation during the raid.”

A government spokeswoman declined to comment. Fernandez denies wrongdoing and says she is being persecuted by President Mauricio Macri. The two may face off in next year’s presidential election.

Fernandez has been indicted on charges she ran a corruption scheme with her public works secretary, Jose Lopez, who was caught stashing millions of dollars in a convent near capital city Buenos Aires. Lopez has struck a deal giving him lenient treatment in exchange for his cooperation in the investigation, according to court documents.

He has been moved from jail to an unknown location.

A local newspaper this month published contents of notebooks kept by a chauffer employed by the Fernandez administration who said he transported bribe money from construction companies to public works officials from 2005 to 2015.

The scandal has further shaken confidence in an economy beset by high inflation and a tumbling peso currency.

The government on Monday unveiled a new system for increasing transparency in the way public works contracts are awarded.

“We know that the so-called ‘notebooks case’ has generated uncertainty,” Transportation Minister Guillermo Dietrich told reporters.