Only days after sending 15,000 troops to the volatile border, Mr Chávez, Washington’s main enemy in the region, ordered the Venezuelan military and people to prepare to “defend the homeland”, claiming that the US planned to use Colombian bases to mount an invasion of his oil-rich nation.

President Uribe of Colombia said in response that he would complain to the UN Security Council and the Organisation of American States, insisting that Colombia had not made any bellicose move towards its neighbour despite threats of war from Mr Chávez.

“Let’s not waste a day on our main aim: to prepare for war and to help the people to prepare for war, because it is everyone’s responsibility,” Mr Chávez said on his weekly radio and television show, Alo Presidente.

The fiery socialist, who narrowly survived a coup attempt in 2002 that some believe was backed by the US, claims that Washington wants to use Colombia to dispose of his revolutionary Government. “The empire is more threatening than ever,” Mr Chávez, a former paratrooper, warned. “Don’t make a mistake, Mr Obama, by ordering an attack against Venezuela by way of Colombia.” Such a war would set the continent alight, he said.

The US and Colombia strongly deny such claims, saying that the deal over the bases, signed slightly more than a week ago to regional unease, only allows the US to mount anti-narcotics and anti-terrorism operations within Colombian territory. Mr Uribe said: “The only thing we are interested in is defeating terrorism related to drug trafficking, which has been so unfair to Colombians for so many years.”

The two nations have long had an acrimonious relationship, with Bogotá accusing Mr Chávez of giving sanctuary and support to left-wing Colombian guerrillas, who cross the border to regroup. It also claims that the Venezuelan authorities are collaborating with paramilitaries and traffickers smuggling drugs out of Colombia, the biggest producer of cocaine.

Mr Chávez, in turn, has accused Colombia of allowing insurrectionists to cross the border to destabilise his country. Before the President ordered the 15,000 extra troops to the 1,375-mile border on Thursday, Venezuela had already beefed up its military presence in the region after a series of killings in recent weeks.

Two Venezuelan soldiers were shot dead last week by four men on motorcycles at a checkpoint in the western border state of Tachira, prompting the Chávez Government to shut crossings temporarily. The bullet-ridden corpses of 11 men, including 9 Colombians, were found in Tachira last month after being abducted from a football pitch. Mr Chávez said that the men were Colombian agents.

Again last month, Venezuela said that it had captured two spies from the Colombian intelligence agency DAS, claiming that behind the espionage lay “the hand of the United States”. Colombia has acknowledged the seizure of one agent but said that he was on holiday in Venezuela and had been arrested in a set-up. Hundreds of people have also been arrested by Venezuelan authorities in the border area for alleged paramilitary involvement.

Speaking to The Times, a senior Colombian government source acknowledged that Mr Chávez often made threats that he did not carry out, but said that he was now “closing the gap between his rhetoric and his actions”.

Venezuela has spent more than $3 billion (£2 billion) on arms recently, mostly from Russia, prompting Hillary Clinton, the US Secretary of State, to warn of a regional arms race. Washington views Colombia as a buffer against Mr Chávez and other Latin American socialists, such as President Correa of Ecuador, President Morales of Bolivia and President Ortega of Nicaragua.

MILITARY STRENGTHS

Venezuela

Army 63,000 men

Navy 17,500

Air 11,500

National Guard 23,000

Reserve Army 8,000

Combat aircraft 94

Submarines 2

Helicopters army 62, air force 34

Colombia

Army 226,352

Navy 30,729

Air 10,150

Reserve Army 54,700

Navy 4,800

Air 1,200

Combat aircraft 117

Submarines 4

Helicopters army 119, air force 114

Source: IISS The Military Balance 2009