Colombia's government has begun exploratory talks with the country's main rebel group to try to end a 50-year-old conflict.

President Juan Manuel Santos announced the move in a TV address, confirming mounting rumours of negotiations, supposedly held in Cuba, between government officials and the left-wing Revolutionary Armed Forces of Colombia (Farc).

"In the coming days the results of the conversations with Farc will become known," said Mr Santos, whose government was able to secure congressional enactment in June of a peace framework law that would provide amnesty to rebel leaders.

Farc, estimated to number about 9000 fighters, suffered major defeats during a decade-long US-backed military build-up from 2000-2010 but has recently stepped up hit-and-run attacks, sabotaging oil and coal mining sites.

Mr Santos said military operations would continue on every single centimetre of national territory during whatever peace process might emerge.

His announcement followed a report by Venezuelan TV network Telesur that Colombia signed an agreement in Cuba to begin peace talks in Oslo, Norway, in October. Colombian officials would neither confirm nor deny those reports.

Mr Santos has faced criticism from his predecessor, conservative hardliner Alvaro Uribe, over his peace overtures to Farc.

The 61-year-old economist, from a prominent newspaper family, was Mr Uribe's defence minister from 2006-2009 and overwhelmingly won the election in 2010.

Mr Santos also mentioned in his address that Colombia's number two rebel group, the National Liberation Army, known by its Spanish-language initials ELN, had expressed a desire to participate in peace.