Senator Cordoba said her Farc links were only to help free hostages
Colombian prosecutors have asked the Supreme Court to investigate three opposition legislators for alleged links to the leftist Farc rebels.
The investigations were prompted by analysis of laptop computers seized in a cross-border raid into Ecuador, said chief prosecutor Mario Iguaran.
Under suspicion is Senator Piedad Cordoba. She has helped mediate the release of six Farc-held hostages.
She said her links with Farc were only to help free the hostages.
Mr Iguaran said five other Colombians and four foreigners were suspected of Farc links, including an Ecuadorean politician and a Venezuelan regional legislator and a US academic.
The other two Colombian legislators under investigation are Senator Gloria Ines Ramirez and Wilson Borja, a member of the lower house of the congress.
The Colombian military raid into Ecuador on 1 March sparked a regional crisis as Ecuador and Venezuela moved troops to their borders with Colombia.
Tensions were finally eased at a regional summit.
Raul Reyes, a senior leader of the Revolutionary Armed Forces of Colombia, or Farc, was killed and laptops seized.
Colombia says their contents show Venezuelan and Ecuadorian support for Farc.
The new investigations come as dozens of current or former members of congress face other investigations over their alleged ties to the right-wing United Self-defence Forces of Colombia (AUC) paramilitaries in what has been dubbed the "parapolitics" scandal.
Most of those being investigated are allies of President Uribe. The president remains popular, however, after overseeing aggressive military action against leftist rebels.
Critics of Mr Uribe see the new investigations as an attempt by the government to deflect attention from the parapolitics scandal.