CARACAS, Venezuela — Colombia’s main rebel group has an intricate history of collaboration with Venezuelan officials, who have asked it to provide urban guerrilla training to pro-government cells here and to assassinate political opponents of Venezuela’s president, according to a new analysis of the group’s internal communications.

The analysis contends that the Revolutionary Armed Forces of Colombia, or FARC, was asked to serve as a shadow militia for Venezuela’s intelligence apparatus, although there is no evidence that President Hugo Chávez was aware of the assassination requests or that they were ever carried out.

The documents, found in the computer files of a senior FARC commander who was killed in a 2008 raid, also show that the relationship between the leftist rebels and Venezuela’s leftist government, while often cooperative, has been rocky and at times duplicitous.

The documents are part of a 240-page book on the rebel group, “The FARC Files: Venezuela, Ecuador and the Secret Archive of Raúl Reyes,” to be published Tuesday by the International Institute for Strategic Studies in London. While some of the documents have been quoted and cited previously, the release of a CD accompanying the book will be the first time such a large number of the documents have been made public since they were first seized.