Colombia's government claimed progress Friday toward saving a peace deal with FARC rebels, but efforts to open talks with another guerrilla group, the ELN, remained suspended over a hostage dispute.

President Juan Manuel Santos said recently he aimed for a "complete peace" through deals with both groups after half a century of war.

Now he is fighting to salvage the peace effort on two fronts.

An accord with the leftist National Liberation Army (ELN) was meant to crown a historic agreement signed last month with Colombia's biggest rebel group, the Revolutionary Armed Forces of Colombia (FARC).

That was until voters surprised the government by rejecting the FARC accord in an October 2 referendum. Critics said the deal was too soft on the FARC.

Santos won the Nobel Peace Prize this month for his efforts. But he admitted there was still work to be done.

- New FARC deal -

After the referendum, Santos's team went back to the drawing board with FARC negotiators in Havana.

They said Friday they had begun drafting a new deal, taking into account the demands of opponents of the earlier accord.

"The proposals are being discussed carefully. Many of them are being incorporated into the text of a new accord," both sides said in a joint statement.

They said they would resume work next week "with the aim of securing a new definitive accord quickly and efficiently."

Santos said his negotiators, meanwhile, would meet again with their political opponents on Saturday to discuss their demands for the new accord.

"Time is pressing, because the ceasefire we agreed is fragile," he said.

"It is a question of goodwill and taking decisions. This can be achieved in days."

- Hostage setback -

Meanwhile, the peace drive suffered another setback this week.

The government on Thursday postponed the official start of talks with the ELN.

Santos complained the ELN had not yet released a hostage, former congressman Odin Sanchez.

ELN negotiator Pablo Beltran said the group had agreed to release Sanchez but had not promised to do so before the dialogue is launched.

The talks were to have been formally inaugurated on Thursday with the first proper sessions of negotiations scheduled for November 3.

Analysts said Thursday's postponement was likely just a hiccup.

"It can't be called a failure yet," said Carlos Alfonso Velasquez, a specialist in conflict analysis.

"But it will be if the talks do not start on November 3, and the ELN knows it."

- Deadly violence -

Colombian authorities estimate the ELN currently has 1,500 members.

That makes it smaller than the FARC, which has some 5,765 members.

Analysts said the ELN also has a different approach to peace talks.

The FARC freed its hostages before peace talks and later declared a ceasefire.

In a reminder of the stakes of the peace bid, deadly violence struck after the ELN talks were postponed.

Two truck drivers were killed in the country's northeast in what the military said was a "terrorist act" committed by the ELN.

"The ELN guerrilla group comes strengthened to the negotiations with the government," Colombia's Conflict Analysis Resource Center (CERAC) said in a report this month.

"Over the past three years this group has increased its level of violence."

- Tough negotiations -

Colombia's ideological and territorial conflict broke out in 1964, when the FARC and ELN were formed.

It has drawn in various groups and killed more than 260,000 people, according to Colombian authorities.

"These negotiations will not be easy," said Ariel Avila, an analyst at Colombia's Peace and Reconciliation Foundation.

"Getting them started will be even harder."