A former leader of Colombia's largest rebel group has been charged in connection with the kidnapping of three US contractors who were rescued from the Colombian jungle last month, the US Justice Department announced Monday.

Heli Mejia Mendoza, known by the alias Martin Sombra, could face up to 60 years in prison after being indicted Friday on seven terrorism and weapons charges by a federal grand jury in Washington.

US Defence Department contractors Marc Gonsalves, Keith Stansell and Thomas Howes were rescued in July along with former Colombian presidential candidate Ingrid Betancourt.

Sombra, who was captured by the Colombian military earlier this year, helped found the leftist Revolutionary Armed Forces of Colombia (FARC) in 1964 and kept watch over the three US contractors during two of their five years in captivity.

Sombra, 55, is one of the highest-ranking FARC members ever captured and oversaw the three contractors' first two years as hostages.

Six other FARC commanders - two presumed dead and four still at large - have also been indicted in connection with the three Americans' time in captivity, the Justice Department said.

Gonsalves, Stansell and Howes were taken hostage in 2003 after their plane crashed in the Colombian jungle during an anti-drug reconnaissance flight. Two other members of their crew were executed by FARC rebels soon after capture.