A Peruvian prosecutor has said that the late Venezuelan President Hugo Chavez and two Brazilian construction companies may have bankrolled Peru's President Ollanta Humala's campaign before taking office in 2011.

An informant gave prosecutors a letter mentioning around $2m in "investments" in Humala's first presidential bid a decade ago, which was signed by Chavez and addressed to Humala.

The letter has not yet been authenticated.

"Burn any evidence, brother, for the good of us all. This is revolutionary, socialist aide," said the letter, as read by prosecutor German Juarez in a televised hearing on Thursday.

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Juarez is in the process of investigating first lady Nadine Heredia for possible involvement in undeclared campaign contributions. She has also been barred from leaving Peru.

No charges have been filed yet, according to Heredia's lawyer.

After losing the 2006 presidential elections, Humala distanced himself from Chavez during his successful 2011 campaign.

Humala has denied taking any money from Chavez.

Another informant alleged that construction companies Odebrecht SA and Grupo OAS, both tangled in a vast corruption scandal in neighbouring Brazil, gave Humala and Heredia hundreds of thousands of dollars.

They also paid the salary of an adviser close to Brazil's Workers Party to help with Humala's 2011 campaign, Juarez said.

Source: Agencies