COLOMBIA'S left-wing Farc rebels have declared a ceasefire from May 20 to May 28, a period including the May 25 presidential election, as the guerrillas and the government continued peace talks in Cuba on Friday.

"We are ordering all of our units to cease any offensive military action against the armed forces or the economic infrastructure as of 0000 hours on Tuesday, May 20, until 2400 hours on Wednesday, May 28," rebel leader Pablo Catabumbo told reporters in Havana.

The Revolutionary Armed Forces of Colombia (Farc) and the government of Colombian President Jose Manuel Santos have been engaged in peace talks since 2012 in an attempt to end a 50-year conflict. Those talks resumed after Catabumbo read the statement.

The Army of National Liberation (ELN), a separate rebel group, is not participating in the talks but was a co-signatory of the cease-fire notice.