The rebels were apparently killed as part of a secret multi-billion dollar operation set up when George W Bush was President.

A covert CIA programme has helped the Colombian government kill at least two dozen rebel leaders, according to the Washington Post.

The paper claims the National Security Agency (NSA) has also provided it with "substantial eavesdropping help".

In addition, the US gave Colombia GPS equipment that can transform regular munitions into "smart bombs" capable of homing in on

targets, even in dense jungles.

The Post says Colombia used smart bombs when it killed a top commander of the Revolutionary Armed Forces of Colombia (FARC) in March

2008.

Paul Reyes was in one of the jungle camps set up by the rebels just across the border in Ecuador when the attack was carried out.

The Washington Post report is based on interviews with more than 30 former and current US and Colombian officials.

It said they had spoken on condition of anonymity because the CIA programme is classified and ongoing.

The CIA would not comment on the Post's report, although Colombian president Juan Santos said the CIA has been "of help", providing

Colombian forces with "better training and knowledge."

The lobby of the CIA Headquarters Building in McLean, Virginia

The CIA has declined to comment on the story

The multibillion-dollar programme was apparently funded secretly and separately from $9bn in aid the US has openly provided to Colombia,

mostly in military assistance.

It was authorised by President George W Bush and has continued under Barack Obama, the newspaper reported.

Colombia's government and FARC have been engaged in peace talks in Havana since late 2012, but there has been no ceasefire between the

two sides.

Earlier this month, President Santos blamed the rebels for an attack on a police post that killed nine people, including civilians, military and

a police officer.

The US-backed military build-up has reduced FARC's ranks to about 9,000 fighters and killed several top commanders,

The rebels, who took up arms almost 50 years ago in 1964, insist they are still a powerful force.