Colombia's leftist FARC rebels on Monday rejected a proposed law under debate in the Andean country's Congress for creating a plebiscite to give the voters final approval over any peace plan.
Guerrillas of the Revolutionary Armed Forces of Colombia (FARC) and the government of President Juan Manuel Santos are negotiating in Cuba to end Latin America's longest war, which has killed 220,000 people and displaced millions over the last 51 years.
"We reject it not only because it is an arbitrary formula, but because it is the safest and least conducive of all the initiatives that are before the Congress of the republic as a result of the peace process," the FARC said in a statement.
After three years of talks, the two sides have set a March 23 deadline to reach a final agreement, which would then be put before the voters for approval.
However, the exact form of that voter approval has generated controversy in Colombia among opponents and supporters of the peace talks alike.
The measure before Congress, and supported by Santos, would create a plebiscite to ratify the peace agreement.
The FARC, which has advocated a national constituent assembly, insists that both sides should determine at the peace table any rules for how the vote should take place.
The government, which opposes the FARC's constituent assembly proposal, expects Congress to approve its proposed law no later than Dec. 16.