BOGOTA, March 20 (Reuters) - Colombian prosecutors on Tuesday began a criminal probe of 20 leading figures, including five former congressmen and two ex-governors, for signing a 2001 document with illegal, right-wing paramilitaries. The investigation extends a growing political scandal that follows the arrest of eight congressional allies of President Alvaro Uribe and his former security police chief on charges they conspired with the militia commanders. "The attorney general's office has formally opened an investigation into these people for conspiring to commit a crime," Attorney General Mario Iguaran told reporters. Prosecutors will seek testimony from those who signed the document with top paramilitary leader Salvatore Mancuso, who is accused of some of the conflict's worst atrocities. Colombia's right-wing paramilitaries were formed in the 1980s by rich ranchers looking for protection from guerrillas fighting in Latin America's longest insurgency. They are accused of massacres, kidnapping and drug-trafficking. Several of the politicians who signed the pact said they had been threatened to make them agree. The document signed in 2001 at a paramilitary stronghold in Santa Fe de Ralito, calls vaguely for a reinforcement of Colombia's rule of law. Rights groups have long charged politicians colluded with the militia gangs. But revelations about their relationship are surfacing after the paramilitaries signed a 2003 peace deal promising them short jail terms for surrendering their arms and giving confessions. Uribe, a U.S. ally who has received billions of dollars in aid from Washington, says he welcomes the probe into militia links so he can purge his government of those tied to criminal organizations. But some U.S. Democrats now controlling Congress say the scandal has cast doubt over the White House request for $3.9 billion in new aid for Colombia and a free trade deal. Since his election in 2002, Uribe has reduced violence from the conflict by sending troops to retake towns and highways once under the control of illegal armed groups. But the largest rebel group, the Revolutionary Armed Forces of Colombia, is still fighting and some militia gangs have also rearmed.
