BOGOTA (Reuters) - President Ernesto Samper put out an urgent call to Colombia`s Marxist guerrillas on Tuesday to begin peace talks soon and then departed for Italy to meet Pope John Paul. Samper offered to set up a demilitarized zone inside Colombia to pave the way for negotiations with rebel leaders or alternatively to arrange a meeting abroad. "The government would accept a demilitarized zone if there was a clear will on the part of armed groups to reach a serious and lasting agreement," Samper said in a speech at Bogota`s presidential palace. The Revolutionary Armed Forces of Colombia (FARC) have insisted on the demilitarization of at least five municipalities as a condition for negotiations but so far both the government and the army have resisted. Samper, who confessed to being an avid reader of the rebel communiques of FARC leader Manuel Marulanda, did not say which specific areas could be demilitarized. Both the FARC, Latin America`s oldest and largest rebel army, and the smaller, Cuban-inspired National Liberation Army (ELN) have until now rejected Samper`s peace plans. Both groups have gained in military and political might over the last year and seem unlikely to sit down to negotiations. Shortly after offering an olive branch to the rebels, Samper left for Italy where he will meet the Pope on Thursday. He is also scheduled to meet Italian president Oscar Luigi Scalfaro and Spanish prime minister Jose Maria Aznar in Madrid before returning on Sunday. In a separate development, ELN rebels in southern Colombia released unharmed five mayors and three other men whom they kidnapped more than a week ago.