BOGOTA, Colombia (AP) _ Leftist guerrillas have freed an American backpacker kidnapped in Colombia last month, officials said Sunday.

Fighters from the National Liberation Army released the hostage _ identified as Glenn Hereggestard of California _ on Friday to the Red Cross in Antioquia province, a foreign diplomat told The Associated Press on condition of anonymity.

The diplomat said it wasn't clear where the rebels abducted Hereggestard or how long he had been held.

A U.S. Embassy official in the capital, Bogota, confirmed that an American abducted by the ELN had been released but said he couldn't identify the hostage.

The official said the hostage required no hospital treatment following his release. It wasn't immediately clear if ransom had been paid.

Leftist guerrillas are responsible for most of the approximately 3,000 people kidnapped annually in this South American nation.

The rebels kidnap for politics and ransom to fund their insurgencies, frequently capturing their victims in roadblocks in a method known as ``miracle fishing.''

The 37-year internal conflict, pitting two guerrilla groups against government troops and a right-wing paramilitary army, kills an estimated 3,500 people every year, mostly unarmed civilians.

The U.S. State Department has placed all three outlaw armies on its list of worldwide terrorist organizations.