Venezuelan President Hugo Chavez has ordered his military to move 10 battalions to the border with Colombia, after Bogota killed a leading rebel. ( BBC )
Speaking on his weekly television show, President Chavez said the country's embassy in Colombia would also close.
Mr Chavez said Colombian President Alvaro Uribe was a "criminal".
He said the killing of Raul Reyes, a top commander of the leftwing Farc rebels, just inside Ecuador on Saturday was a "cowardly murder".
Mr Chavez has been mediating with Farc to secure the release of hostages the rebels hold.
But he lamented the killing of Reyes and at least 16 other Farc rebels when he spoke on his show, "Alo, President".
"It wasn't any combat. It was a cowardly murder, all of it coldly calculated," Mr Chavez said.
Mr Chavez had earlier warned Bogota that any similar incursion into Venezuelan territory would be a "cause for war".
The incursion has also been condemned as "scandalous" by Ecuador's President Rafael Correa.