BOGOTA (AFP) - Nearly five tons of marijuana held by Colombia's FARC rebels was seized, authorities said on Tuesday, as ongoing negotiations between the guerillas and government are currently focused on illegal drugs.

A total of 4,976 kilos of marijuana were seized from rural drug storage facilities in the central department of Meta, during an operation on Sunday, the Anti-narcotics Police Directorate said.

The operation also found and destroyed 4.9 hectares of marijuana.

Illegal drugs are one of the main discussion points on the agenda for the FARC and the government of Juan Manuel Santos, who have been in peace negotiations in Cuba for the past 15 months.

The area housing the marijuana fields and drug facilities was guarded by 53 rebels and authorities are determining whether the guerillas only protected the area or also owned the drugs.

The government and FARC have already reached consensus on rural development and political participation in their negotiations. Yet to be broached are reparations to the victims of the conflict, disarming of the rebel forces and agreement on the mechanism for endorsing a resolution.

The Revolutionary Armed Forces of Colombia - the country's largest and oldest rebel group, which was established in 1964 - has 7,000 to 8,000 fighters.

In addition to producing marijuana, Colombia, along with Peru, is the world's largest producer of cocaine, accounting for some 309 tons in 2012, according to the UN.