The organisation's call comes after information emerged that three US citizens, apparently contracted by the US Central Intelligence Agency (CIA), may have been taken captive by the FARC following the crash of the plane they were travelling in. The plane crashed close to Florencia, department of Caquetá in southern Colombia, an area with a heavy FARC presence.

Two other men - a US citizen, Jennis Thomas, and a Colombian army sergeant, Luis Alcides Cruz, - were reportedly found dead with bullet wounds. The Colombian authorities claim the latter were executed.

'If FARC guerrillas killed these men hors-de-combat, this would be a serious violation of international humanitarian law,' Amnesty International said.

With regards to the three other passengers, Amnesty International stated that if they are being held by FARC guerrilla forces it is essential that their physical security is guaranteed and that they should have access to any medical attention they may require.

Background

In recent years, the US administrations of Presidents Bill Clinton and George Bush have been providing the Colombian security forces with increasing amounts of military aid. This aid, within the so-called Plan Colombia and subsequently the Andean Regional Initiative aid package, was ostensibly for use in the 'war on drugs'. Yet the distinction between the 'war on drugs' and the counter-insurgency war against left-wing guerrilla groups - of which the FARC is the largest - has been increasingly blurred.

Last year, the US administration secured congressional approval for lifting a previous requirement that limited aid to counter-narcotics efforts so that military aid approved to date can also be used to combat activities by illegal armed groups considered to be 'terrorist' organisations including the FARC.

The aid provided to the Colombian security forces has included:

• the provision of helicopters to military units,
• training, and
• military aerial intelligence.

Some of this aid has been provided through companies sub-contracted by the US State Department, the Pentagon or the CIA.