Oscar Tulio Lizcano, 62, was rescued in an early morning raid in the remote jungle of western province of Choco, said Henry Murillo, the No. 2 official in Caldas province, where the lawmaker was originally abducted.
Details of the rescue from the Revolutionary Armed Forces of Colombia, or FARC, Latin America's last remaining major rebel army, were promised in a news conference scheduled for later Sunday by Defense Minister Juan Manuel Santos.
"He was rescued in an area of thick jungle," the eldest of Lizcano's two sons, Mauricio, told The Associated Press by telephone. He said President Alvaro Uribe called him early Sunday with the news, and said his father was a bit weak.
Martha de Lizcano wept upon being told of her husband's rescue.
"It's been eight years of great suffering," she told Caracol radio.
Presidential spokesman Cesar Velasquez told the AP that the Conservative Party congressman was being flown for a medical exam to the western city of Cali.
Lizcano was kidnapped on Aug. 5, 2000. Government officials in recent weeks said FARC deserters had reported that his health was delicate, though without offering details.
The rescue comes nearly four months after Betancourt, a dual French national, and the three Americans were freed in a sophisticated ruse engineered with the help of a rebel turncoat in which Colombian military agents posing as humanitarian workers helicoptered 15 FARC-held hostages to freedom without a shot being fired.
In April, the FARC had released a so-called "proof-of-life" video of Lizcano in which he pleaded with Venezuelan President Hugo Chavez to do "the utmost to get us out of here because we are rotting in the jungle."
The FARC still holds at least 20 high value politicians, police officers and soldiers - including a provincial governor and a police colonel, some of whom have been held for more than a decade.
It has been seriously weakened in the past two years by a military that has been fortified and become more professional and agile under Uribe thanks in considerable measure to U.S. training, advising and intelligence-gathering.
By Associated Press Writer Vivian Sequera