Hugo Chávez, the president of Venezuela, is paying a surprise visit to Colombia this week. His aim is as remarkable as it is ambitious: to strike a deal with the FARC guerrillas and secure the release of the hostages they are holding in the rain forest.

The visit has been meticulously planned. Mr Chávez is to meet with Colombian president Álvaro Uribe at his ranch outside the capital Bogotá. At the top of the agenda is Mr.Chavez's offer to negotiate directly with Colombia's FARC guerrillas.

The aim would be to reach a humanitarian agreement securing the release of the hostages the FARC is holding, in return for around 500 guerrillas currently held in Columbian gaols. The best known of the hostages is the former presidential candidate Ingrid Betancourt, who also has French citizenship.

Mr Chávez has had long-standing good relations with the FARC. Venezuelan officials are said to have held meetings with the guerrillas in the Colombian rain forest and it is generally assumed that Venezuela has also given them financial support. Such reports only serve to heighten the tensions between the left-wing Mr Chávez and right-wing Mr Uribe. This makes the Venezuelan leader's visit all the more remarkable.

Hard line

Mr Uribe is under heavy pressure in his own country to find a way out of the FARC hostage crisis. Family members are appealing to the government to make concessions. There is even a national radio station with programmes for the hostages' families.

Up to now Mr Uribe has opted to take a hard line against the FARC, deploying troops with varying success. There have been major improvements in security in the country, and many roads have been reopened for traffic, but the hostage crisis goes on. On 15 Augustus Mr Uribe gave permission for an opposition senator, Piedad Córdoba, to start negotiations with the FARC. Mr Córdoba then travelled to neighbouring Venezuela to discuss the matter with Mr Chávez.

France has also been putting pressure on Mr Uribe to reach a deal with the FARC. The country has been campaigning for the release of Ingrid Betancourt, who also holds a French passport, since her kidnapping in 2002. President Nicolas Sarkozy has offered Mr Chávez his full support. The United States remains aloof, even though the FARC is still holding three US citizens prisoner, Thomas Howes, Keith Stansell and Marc Gonsalves.

Heavy armed guerrilla movement

So far the FARC has shown little flexibility. The movement is only prepared to negotiate in a specially created demilitarised zone. Mr Uribe has refused to agree to this, and not entirely without good reason. Under the previous president, Andrés Pastrana, a similar zone was established, which the FARC then used to rearm and reorganise its guerrillas.

The FARC, the Revolutionary Armed Forces of Columbia, started life as a farmers' movement campaigning for fairer land distribution. More than forty years ago it then began an armed struggle, initially on a small scale. Over time it transformed into a heavily armed guerrilla movement with thousands of fighters. It funded the growth with income from the drug trafficking and kidnapping operations in which it came to specialise.

It is hard to assess whether Mr Chávez is genuinely capable of forcing an opening in the stalemate that has existed for years between the Colombian government and the FARC. He too has a lot at stake. In many Western countries he is accused of being a ruthless dictator with contempt for democracy. How will it affect his international standing if he emerges as a peacemaker in Colombia?