A diplomatic offensive seeking support throughout Latin America had found a providential friend in Hugo Chavez, the Venezuelan president, El Pais said in the latest of a series accusing Chavez of secretly helping FARC.
The daily had claimed on Saturday that Chavez allegedly tried to arm Farc with help from the former Soviet republic of Belarus.
El Pais quoted a message in a February 8 email from Ivan Marquez, a Farc leader, saying Chavez had considered with Belarus authorities the possibility of providing weapons to Farc.
The email was alleged to have been found in the files of a seized computer of Reyes, who was Farc's second-in-command when he was killed in March in Ecuador during a Colombian cross-border military raid, El Pais said.
Venezuela says the computer files are not genuine.
The El Pais
report said the Farc's diplomatic strategy was launched in 2002 at a difficult time for the fighters because they had just been added to a European Union list of terrorist organisations.
El Pais reported last December that Venezuela had become a safe haven for Farc, currently harbouring several camps on its territory.
Venezuela has denied the charge.
The Wall Street Journal had reported on Friday that US intelligence officials believed the seized computer files showing strong connections between Chavez and Farc, were authentic.
The files described meetings between Farc commanders and senior Venezuelan officials including Chavez himself, the Journal said, based on its review of more than 100 documents allegedly seized from Reyes's computer.