GENEVA — A former first lady of Peru who began working for the U.N. food agency last week has requested an unpaid leave of absence as she faces an investigation back home into whether she received illegal payments.

The Food and Agricultural Agency did not indicate whether it had granted Nadine Heredia's request for leave from her post as the FAO's liaison officer at the U.N. European headquarters in Geneva. An agency statement provided Friday to reporters in Geneva said she has been an FAO employee since Nov. 24.

The Peruvian government is seeking the cancellation of Heredia's appointment, which can confer immunity from prosecution.

Heredia faces investigation for allegedly receiving illegal payments from Brazilian construction firms and Venezuela's government when her husband, Ollanta Humala, ran for president in 2006 and 2011.