After announcing the decision, Venezuelan President Hugo Chavez ordered maximum vigilance at the border.

Colombian President Alvaro Uribe is capable of anything in his last days in power, Chavez said, after dismissing alleged proof of the presence of Colombian guerrilla forces (FARC and ELN) in Venezuela.

Shortly after Chavez's announcement, Venezuelan Foreign Minister Nicolas Maduro affirmed the government was assessing a package of preventive and protest measures.

Other measures are been studied for the economic and aeronautic fields, aimed at defending the country's dignity, he stressed.

As one of the first steps, the Colombian diplomatic corps was asked to leave the country within 72 hours, and Venezuela's diplomatic staff in Bogota was told to return.

In addition, the Venezuelan government called upon the Union of South American Nations to convene a council of foreign ministers to analyze Colombia's increasing aggressiveness.

In statements to the press, Maduro asked the people to actively support their government, and warned of possible actions by the domestic opposition in support of the outgoing Colombian administration.

The escalation of Colombia's anti-Caracas attacks is seen in Venezuela as an attempt to undermine future dialogue between the two nations, whose relations came to a deadlock in 2009 after seven US military bases were installed in Colombia.