BOGOTA, Colombia -- The Colombian Defense Ministry said Saturday that it has information from various intelligence sources that the leader of Latin America's largest guerrilla army is dead.
In a statement, the ministry said "we have learned through different military intelligence means" that the commander of the Revolutionary Armed Forces of Colombia, Manuel "Sureshot" Marulanda, died March 26.
"We know that inside the FARC, the version is that he died of natural causes, specifically from a heart attack," the ministry said.
Marulanda is believed to be about 80.
First word of Marulanda's possible death came earlier Saturday when the newsmagazine Semana quoted Defense Minister Juan Manuel Santos as saying he had information that Marulanda died in the guerrillas' southern Colombian stronghold at the time of three bombing raids.
"Whether the death of Marulanda came in a bombardment or from natural causes, this would be the most serious blow this terrorist group has suffered," the Defense Ministry statement said.
In the Semana interview, Santos said that the government had been told of the rebel leader's death from a "source who has never failed us."
A senior defense official said the military's main intelligence source is human and that communications intercepts support the claim -- but he cautioned that Marulanda's actual death remains to be confirmed. The official, who was not authorized to discuss the issue, spoke on condition of anonymity.
Marulanda, whose real name is Pedro Antonio Marin, has led the peasant-based FARC since its founding in 1964. Colombia's government has announced his death various times over the past 15 years, but each time proof that he was alive cropped up months later.
"If [the FARC] are going to say that the information we have is not true, they should show him," said the statement, which was read by the military's chief of staff, Adm. David Moreno.
The FARC did not immediately respond on the Web sites that publish rebel communiques.
The ministry's announcement and the Semana article Saturday follow a series of rebel setbacks. The past year's blows include the March killings of rebel commander Raul Reyes and another member of the rebel's seven-man ruling Secretariat and the defection last weekend of a female leader well regarded inside the rebel group.
The military also said that Marulanda has been replaced as FARC leader by a rebel ideologue known as Alfonso Cano. The army has for months said it has Cano cornered in the southwest Colombian jungle and that his death or capture is imminent. FARC statements have denied Cano is in the area.
Born to a poor peasant family, Marulanda was radicalized by the vicious civil wars that ravaged Colombia in the middle of the last century, pitting Liberals against Conservatives.
He and other survivors of a 1964 army attack on a peasant community escaped to the mountains and formed the FARC, which grew over the decades to include some 15,000 fighters. The defense minister now estimates the FARC's strength at around 9,000.
Marulanda's deadly aim in combat against the army earned him the name "Sureshot."
Notoriously reclusive, he is said to have never set foot in Colombia's capital or to have left the country, giving just a handful of interviews over the course of his life.
Even senior commanders within the FARC speak of Marulanda with awe, and he is known to have the final word over any major decision taken by the FARC.
The guerrillas remain strong in many parts of Colombia's countryside, but many Colombians believe they have abandoned their communist ideology as the movement has come to rely chiefly on drug trafficking as its main funding source.
The government says the FARC currently holds 700 hostages, including three U.S. military contractors and French-Colombian Ingrid Betancourt, who was running for president when the rebels kidnapped her in 2002.