Mr Pastrana extended rebel safe-zone period

He spoke to community leaders in towns and villages about life under the rebels.

On Thursday, he will hold talks with the FARC leader, Manuel Marulanda.

The BBC correspondent in Colombia, Jeremy McDermott, says Mr Pastrana has little to show for giving the FARC its safe haven and the Colombian public is becoming increasingly frustrated by the lack of progress towards peace.

Open letter

The FARC broke off negotiations last November, insisting they would not return until the government had done something to halt the advance of paramilitaries and stop their strategy of killing suspected guerrilla sympathisers.

Mr Pastrana on Saturday drove himself around the rebel enclave with only one bodyguard for protection.

He also extended until 9 February the 1998 agreement giving FARC the 42,000-square-kilometre area for peace talks.

FARC has given no ground in the peace talks

After reaching the town of Uribe at around 9.30am local time (1430 GMT) on Saturday, Mr Pastrana also visited the municipality of Macarena, stopping to speak with community leaders in both places, before moving on to San Vicente del Cagun.

Mr Pastrana annouced Thursday's meeting with Mr Marulanda in an open letter to the rebel leader, which was read out to reporters in the capital Bogota.

Possible concessions

"The entire nation and the international community is confident we shall be able to obtain results fundamental to the peace process," he wrote.

The two leaders are expected to discuss prisoner exchange, right-wing paramilitary groups, and Plan Colombia - the president's drug-fighting initiative backed by $1.3bn from the US.

The FARC claims the initiative is simply a plan for war.

Our correspondent says analysts feel that Mr Pastrana is going to have to offer more concessions on Thursday - probably another long renewal of the safe haven and a prisoner exchange - to get the FARC back to the peace table.