Peru's President Alejandro Toledo has again accused the Venezuelan leader, Hugo Chavez, of interfering in Peru's presidential election, due on 4 June.
Peru's election featured prominently in President Chavez's weekly show
Mr Toledo urged the Organization of American States (OAS) to act over what he termed Mr Chavez's meddling.
Mr Chavez has called front-runner Alan Garcia a "thief", saying Venezuela will not have ties with Peru if he wins.
A run-off election on Sunday will pitch Mr Garcia against nationalist candidate Ollanta Humala, who Mr Chavez backs.
The war of words between the two South American presidents has been simmering for several weeks.
At the start of May, Mr Toledo withdrew Peru's ambassador from Caracas after President Chavez publicly endorsed Mr Humala and criticised Mr Garcia. Venezuela responded by withdrawing its envoy from Lima.
Opinion polls suggest a lead for Alan Garcia
Over the weekend, Mr Toledo said the regional body, the OAS, had to make a pronouncement regarding Mr Chavez's frequent interference in Peruvian politics.
The OAS "must not wash its hands" of the issue, he said and warned Mr Chavez "not to mess with my country".
On Sunday, Mr Chavez, who hosted his weekly radio programme "Hello President" from Bolivia, accused Mr Toledo of being "subordinate" to US interests.
He called Mr Garcia "an irresponsible demagogue and thief", the candidate of the Peruvian oligarchy, the right wing and the US empire.
"Hopefully the Peruvian people, who we love, will give a demonstration next Sunday of historical consciousness and allow Ollanta Humala to be Peru's next president," he said.
Mr Garcia, on the campaign trail in Lima, hit back at Mr Chavez on Monday.
"He's nouveau riche thanks to the oil and he wants to extend his autocratic militaristic model to various countries in the region," said Mr Garcia.
Mr Garcia, who was president from 1985 to 1990, is ahead of Mr Humala with less than a week to go before the elections, the latest opinion polls suggest.