Venezuela has claimed to have busted a plot to assassinate President Nicolas Maduro, arresting two hitmen it said wanted to kill the leader on orders from a Colombian ex-president.

The Interior Minister Miguel Rodriguez said on Monday the two hitmen were arrested on August 13.

The pair, Victor Johan Guache Mosquera and Erick Leonardo Huertas Rios, were part of "a group of 10 men who were coming to carry out the murder of the president", working with former Colombian president Alvaro Uribe, Rodriguez charged.

Maduro himself called on the US President Barack Obama to say if he ordered or knew of the alleged assassination plan.

"Is President Obama so weak that decisions are made for him in the United States to kill a Latin American head of state without his knowing it?" Maduro said.

The Colombian ex-president, who held office from 2002-2010, vehemently denied the plot, branding the allegations as "slurs".

In an interview with the Colombian television, Uribe said he would rather talk about "important issues and not the slurs of the dictatorship".

The Venezuelan opposition leader Henrique Capriles, who lost the April presidential vote to Maduro and is contesting the results, shrugged off the alleged plot, saying: "Nobody believes that tall tale."

Rodriguez in June alleged that Maduro was targeted by a separate assassination plot launched from Colombia and the US.

Venezuela made frequent allegations of assassination plots against the late leftist President Hugo Chavez and has continued to do so under Maduro, his handpicked successor.

Source: Agencies