The Colombian government and FARC rebels reached a deal Saturday on searching for the thousands missing and presumed dead in their decades-long conflict, in a further step toward peace, diplomats said.

The fighting between the two sides has killed more than 220,000 people and uprooted six million since the Revolutionary Armed Forces of Colombia (FARC) was launched in 1964 in the turbulent aftermath of a peasant uprising.

But Bogota and the leftist guerrillas began peace talks in the Cuban capital Havana in November 2012 and announced a major breakthrough last month.

Saturday's agreement launches steps to search for and locate those missing, as well as identify and return their remains, Cuban diplomat Rodolfo Benitez told reporters.

It also sets up a special unit to focus on the task with support from the International Committee of the Red Cross and Colombia's National Institute of Legal Medicine and Forensic Sciences, he added.

The new unit will seek to determine the exact number of people missing, estimated at about 51,000.

Norwegian diplomat Dag Nylander said the unit would strengthen and streamline the process for identifying remains, as well as coordinate and speed up the search and identification process.

Both Cuba and Norway are shepherding the peace process and the diplomats addressed the press in the presence of delegations from both sides.

Bogota and the rebels agreed to share information about those missing and where unidentified victims have been buried, the diplomats said.

In September, government and rebel negotiators signed a deal on justice for crimes committed during the conflict, which had been the key issue blocking progress in the peace talks.

Experts hailed the move as a milestone and Colombian President Juan Manuel Santos vowed that the two sides would sign a definitive peace deal within six months.

However, the FARC have since warned that an agreement would not be possible in that timeframe if Bogota backtracks on the partial deal.

The FARC, the largest leftist guerrilla group still active in Colombia, has an estimated 7,000 fighters.