Prosecutors in Peru have opened a money laundering investigation against Nadine Heredia (photo right). She is chair of the Nationalist Party (PN), a potential candidate for the April 2016 presidential election and wife of current President Ollanta Humala (photo second right).

Heredia is accused of receiving unexplained income in her bank account at the same time as President Humala allegedly received illicit funds from Venezuelan companies.

Prosecutors said a total of $215,000 (192,000 euros) were used by her husband to finance his presidential campaign. Humala has been president since 2011.

Handwriting experts have been asked to examine bank deposit slips allegedly signed by Heredia.

There are also allegations that President Humala received funds from the late President Hugo Chavez of Venezuela for his 2006 campaign. Last week, Humala denied receiving $400,000 from Brazilian construction company Odebrecht which did not appear in tax records in 2006.

Prosecutor German Juarez in Lima has widened his investigation to include Heredia's brother, Ilan Heredia, who is also treasurer of the PN, and businessman and former advisor to President Humala, Martin Belaunde Lossio. The latter was extradited from Bolivia in May.

Earlier this week, Heredia was questioned by prosecutors over four journals alleged to have information about money from Venezuela that were related to election funding.

"I have come to fulfill this statement I have said, repeatedly, that the documents submitted today, such as journals, notebooks and the content of the journals and notebooks are not my property," Heredia said to prosecutor Juarez.

The latest opinion polls indicate that Humala's popularity has fallen to 13 percent, in part due to the allegations against his wife.

jm/lw (EFE, AFP)