BUENOS AIRES (Reuters) - Three Argentine judges ordered that a key official in former President Cristina Fernandez’s government be detained on Tuesday as part of a probe into an alleged case of fraud.

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The request to detain former planning minister and current lawmaker Julio De Vido comes five days before the country’s parliamentary elections in which Fernandez is seeking a Senate seat.

De Vido, who as planning minister was in charge of running energy infrastructure projects, is under investigation in a case involving the Patagonian coal mine Rio Turbio, which prosecutors say is underproducing despite receiving multi-million dollar investments from the state.

Reuters was not able to reach De Vido for comment. In July, he gave an interview to a radio station in which he denied any wrongdoing in the case.

In an official ruling, the judges said De Vido should be jailed because of the risk of him fleeing or interfering with the case.

“His imprisonment is the only viable alternative for ensuring the success of the investigation,” the ruling said.

De Vido cannot be arrested unless Congress agrees to strip him of his parliamentary immunity. Past efforts to strip lawmakers of parliamentary immunity have mostly proved futile in Argentina.

Fernandez, who governed the country from 2007 to 2015, remains the main force of opposition to center-right President Mauricio Macri. Polls show her coming a close second ahead of an Oct. 22 Senate race in Argentina’s largest province of Buenos Aires, behind Macri’s preferred candidate.

That result would still guarantee her a Senate seat and immunity from arrest, but is seen lessening her chances of making a new run for the presidency in 2019.

The former president’s time in office has been peppered with corruption accusations, some of which have involved De Vido.

Fernandez, the subject of corruption investigations herself, has acknowledged there was likely corruption during her government but denies personal involvement.