Colombia's president Andres Pastrana has rejected demands by left-wing rebels, delivered in a new ultimatum this week. The rebels are insisting the government stop calling them terrorists.

The rebels announced seven demands, most of which focus on threats to their safety in the demilitarized zone, set up two years ago to create a safe haven for talks. The rebels control the zone but the FARC complains that it is being threatened by military aircraft and an army build-up around the periphery.

But the rebels made another, unexpected demand: that the Colombian government publicly state that the FARC is a political organization, and not a terrorist group. The U.S. government has included the FARC on its international terrorist list. The FARC is clearly concerned that the designation might turn the international community aggressively against it.

President Andres Pastrana flatly turned down the guerrillas' demand for an image boost. "They're the ones who define themselves to the world," he said. "It's not up to me, as president to do that. If they keep kidnaping and attacking villages," the president added, "it is because they want to be seen as terrorists."

Colombia's peace process has been shaky and unproductive for months. The government accuses the guerrillas of having no real interest in coming to an agreement. The guerrillas accuse the government of putting their negotiators in the demilitarized zone at risk.

Guerrilla spokesman Raul Reyes insisted the government meet the guerillas' demands. "If the government does not accept our proposals," said Mr. Reyes, "it will be necessary to officially hand back the five municipalities in the demilitarized zone."

This is the first time the FARC has directly threatened to give up control of the demilitarized zone, a move that would end two years of peace negotiations. Despite concern for the peace process, government leaders reacted to the ultimatum with scorn. Colombian president Andres Pastrana vowed Thursday not to weaken government controls around the zone.

Many Colombian leaders are urging the government to try to save the peace process, fearing the end of talks would usher in a bloody new period of heightened warfare. And yet, there is increasing belief that the guerrillas are demanding the impossible and that the government's room to maneuver is almost zero.