FARC regards Plan Colombia as US imperialism

Observers say there is little hope of a major breakthrough, but the talks should encourage Mr Pastrana to extend the demilitarised zone beyond its current 9 February expiry date.

The FARC staged a show of force on Wednesday in advance of Mr Pastrana's visit, with about 100 guerrillas practicing a drill in the town of San Vicente.

Fighting for four decades

The Marxist movement is Colombia's oldest - it has been fighting for 37 years - and most powerful, with between 12,000 and 16,000 fighters.

Its leader, Manuel Marulanda, is expected to discuss three issues with Mr Pastrana on Thursday:

• the exchange of prisoners

• right-wing paramilitary violence against actual or perceived FARC supporters

• President Pastrana's US-backed Plan Colombia, aimed at reducing the cocaine trade on which the FARC is believed to rely for its funds

About 100 FARC guerrillas marched on Wednesday

Mr Pastrana has staked his career on bringing an end to the violence that causes the death of about 3,000 Colombians a year.

His creation of a 42,000sq km safe haven for the FARC has been widely criticised in Colombia, and a rebel demand to create a similar demilitarised zone for another guerrilla group, the ELN, has not gone down well with the public.

Critics say Mr Pastrana has made too many concessions, while the rebels have continued fighting, recruiting and distributing propaganda.