Senator Jaime Dussan, of the left-wing Democratic Poll, said Farc commanders contacted the party and informed them that the new leader was Alfonso Cano.

Cano's real name is Guillermo Leon Saenz and he has been the ideological head of the guerrilla army.

Long-time leader Manuel Marulanda has died or is about to die of prostate cancer, say intelligence sources.

Marulanda is reported to have been suffering from terminal cancer

The news marks the end of an era for the Farc, one of the world's richest and most powerful guerrilla armies.

Manuel Marulanda built the rebel force up from 48 fighters to the 16,000-strong army of today and, in doing so, became a legend in Colombia.

His successor, Alfonso Cano, has been the movement's ideological head for over a decade.

Analysts believe that the announcement reveals a shift away from the military emphasis of the Farc to more political activity.

Many think this could raise the chances of a political dialogue with the government.

The Farc have been fighting for 40 years to overthrow the government and install a Marxist regime.

Cano is known as a committed communist and the movement's ideology is unlikely to change.

What may change is that the group may move away from indiscriminate bombings and killings that have earned the Farc the label 'terrorist organisation' both in the United States and Europe.