Colombian President Alvaro Uribe says he will ask the International Criminal Court to bring genocide charges against President Hugo Chavez of Venezuela.
He accused Mr Chavez of sponsoring and financing Colombian Farc rebels. Venezuela denies the charge.
Colombian officials say a laptop found during a raid on a Farc camp held files indicating Venezuela gave Farc $300m.
Colombian forces entered Ecuadoran territory to raid the camp, provoking protests and a diplomatic crisis.
Venezuela and Ecuador have broken off ties with Colombia and moved troops to the Colombian border.
"Colombia proposes to denounce the president of Venezuela, Hugo Chavez, in the International Criminal Court for sponsoring and financing genocide," Mr Uribe said.
In Washington, President George W Bush said the United States fully supported Colombia. He condemned what he called "provocative manoeuvres" by the Venezuelan government.
Saturday's incursion by Colombian forces saw the killing of senior Farc commander Raul Reyes, and 16 others.
Colombian Vice-President Francisco Santos, speaking earlier at a disarmament conference in Geneva, said evidence of plans to make a dirty bomb - a bomb using radioactive material - was also found on the computer.
Reyes was Farc's first secretariat member to be killed in combat
Latin American powers including Chile, Mexico and Brazil have offered to mediate in the dispute. An emergency meeting of the Organization of American States is being held to discuss the crisis.
Farc - the Revolutionary Armed Forces of Colombia - has been fighting for more than four decades with the declared aim of fairer wealth distribution.
However, analysts say it funds itself mainly through the cocaine trade, while holding hundreds of hostages it has kidnapped for ransom and political ends.
President Chavez and Venezuela have been involved in recent talks to free some of them.
In a statement, Farc said the raid had "dealt a serious blow" to negotiations for the release of the highest-profile hostage, the former Colombian presidential candidate Ingrid Betancourt.
She also holds French nationality by marriage.