Interpol, the global police agency, has said that documents on laptop computers found following a Colombian attack on a Farc rebel base in Ecuador in March were not tampered with.
Colombia alleges the documents show that Venezuela and Ecuador aided the group, but both nations say the claims are a US-backed smear campaign.
"Interpol concludes there was no alteration," the agency's secretary-general, Ronald Noble, said on Thursday following the release of a report into the seizure.
The agency said it was not in its remit to assess the validity of Colombia's allegations against Venezuela.
Colombia had invited Interpol to perform forensic tests on the three laptops and other hardware taken from the camp following the March 1 raid after accusations from Hugo Chavez, the Venezuelan president, that the documents were fakes.
The Colombian attack left Raul Reyes, the Farc second-in-command, and 24 others dead.
Interpol said Colombian authorities did not always follow internationally accepted methods for handling computer evidence but did not
modify, delete or create any user files.
"No one can ever question whether or not the Colombian government tampered with the seized Farc computers," Noble said.
"We are absolutely certain that the computer exhibits that our experts examined came from a Farc terrorist camp."
In Caracas, Chavez denounced Interpol's conclusion, saying: "Do you think we should waste time here on something so ridiculous?"
He called Noble "a tremendous actor" and "an immoral police officer who applauds killers" - referring to the Colombian raid.
Chavez also said his country was revising its diplomatic, economic and political relations with Colombia.
Chavez has denied arming or funding the Revolutionary Armed Forces of Colombia (Farc), although he has urged the Colombian government to negotiate with the group.
On Thursday the US said the there were "serious allegations" that Venezuela had supplied arms and support to what it described as "a terrorist organization''.
"Certainly, that has deep implications for the people of the region," Sean McCormack, a US state department spokesman, said.
Al Jazeera's Lucrecia Franco in Venezuela says if the US concludes that Ecuador and Venezuela have been sponsoring the Farc, they could in turn be branded sponsors of terrorism, which could have grave economic and diplomatic implications for both nations.
The cross-border raid in March ignited a regional diplomatic crisis between Colombia and neighbouring Ecuador and Venezuela, who sent troops to their borders following the incident.
Farc has been fighting a civil war against the Colombian government for decades. Thousands have died in the conflict.