By Nelson Acosta
HAVANA, May 16 (Reuters) - Colombia's leftist FARC rebels declared a unilateral cease-fire from May 20 to May 28, a period including the May 25 presidential election, as the guerrillas and the government continued peace talks in Havana 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 in Havana since November 2012 in an attempt to end a 50-year-old 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.
Any developments in the peace talks stand to affect the presidential election, in which center-right President Juan Manuel Santos is seeking re-election.
Once a clear front-runner and a strong supporter of the peace process, Santos has seen his lead shrink in public opinion polls.
Right-wing candidate Oscar Ivan Zuluaga has pulled even in the polls. Zuluaga belongs to the party of former President Alvaro Uribe, whose popularity rose by taking a hard line against the FARC, and Zuluaga has threatened to break off peace talks if he wins and the FARC does not declare a definitive cease-fire.
However, neither of the top two candidates appears likely to get the 50 percent necessary to win on May 25, which would force a run-off on June 15.
Peace negotiators are attempting to end Latin America's longest-running guerrilla war, which has killed more than 200,000 people since it began in 1964. (Reporting by Nelson Acosta; Editing by Daniel Trotta, W Simon and Bernadette Baum)