Hugo Chavez denied claims that Venezuela sold arms to Farc rebels
Venezuelan President Hugo Chavez has announced trade measures against Colombia, amid a growing diplomatic row between the two nations.
Mr Chavez said he would halt the import of 10,000 cars from Colombia and ban a Colombian energy firm from exploring Venezuela's oil-rich Orinoco region.
Last week, Mr Chavez recalled his envoy from Bogota over accusations Venezuela had provided arms to Colombian rebels.
He is also angry at plans to allow US troops to use Colombian military bases.
Colombian President Alvaro Uribe is currently touring South America to try to reassure fellow leaders over the planned accord with Washington to allow US troops to use several bases.
A number of South American nations - including Argentina, Brazil and Bolivia - have expressed concerns over Bogota's plans.
However, Peru has expressed support for Mr Uribe, while Chile and Paraguay have said the accord is an internal matter for Colombia.
Washington wants use Colombia as a regional hub for operations to counter drug-trafficking and terrorism.
The US has been forced to look for a new location after the Ecuadorean government refused to renew the lease on its Manta base that the US military was using.
Speaking at a news conference in Caracas, Mr Chavez said the Venezuelan government would halt the import of 10,000 vehicles from neighbouring Colombia.
He also said Colombia's Ecopetrol company would be barred from taking part in an auction to develop the heavy crude in Venezuela's Orinoco region.
Mr Chavez went on to say Venezuela would seek to buy "several battalions of Russian tanks" during his visit to Russia in September.
"These bases could be the start of a war in South America," Mr Chavez told reporters. "We're talking about the Yankees, the most aggressive nation in human history."
Mr Chavez also rebuffed Bogota's accusations that Caracas had given weapons to the left-wing Farc rebel group.
Alvaro Uribe is Washington's main ally in the region
He said that rocket launchers and automatic rifles found in a Colombian rebel camp had been stolen from a Venezuelan naval post 14 years ago.
The Venezuelan leader identified a wide range of products that Venezuela imported from Colombia, including meat, dairy and cereals, saying he would be looking for other nations to do business with.
"We're going to replace all of these imports.
"It's our responsibility because at any stage Yankees could say 'send no more meat to Chavez' or 'don't send the Venezuelans', because it is the Yankees who are going to rule over there - not Uribe," Mr Chavez said.
Colombia is a vital provider of food, plastic goods and automobiles to Venezuela, in exchange for gas from the Opec member, says the BBC's Will Grant in Caracas.
Bilateral trade between Venezuela and Colombia amounts to about $7bn (£4bn) a year, and some analysts suggest it will not be easy for Mr Chavez to replace it, he adds.
But our correspondent says that Mr Chavez remains adamant that it can be done, saying that Venezuela's "trade with Colombia isn't indispensible".
A close Chavez ally, Bolivian President Evo Morales, said on Wednesday that Washington was using Colombia's Farc rebels as an excuse for military operations in the region.
"We can't have all these planes and military equipment concentrated in Colombia
This isn't against drug-trafficking, it's against the region. Our duty is to reject it," said Mr Morales, a day after his meeting with Mr Uribe.