Bogota: Colombian prosecutors arrested President Alvaro Uribe's cousin on Tuesday as authorities probed his suspected ties to paramilitary death squads in a deepening political scandal for the key US ally.

The investigation of Mario Uribe, a longtime senator and presidential confidant, is expected to fuel concerns among US Democrats who oppose a Colombian trade pact because of human rights abuses and lingering influence of ex-paramilitaries.

Jostling with screaming protesters, police spirited Mario Uribe away from the Costa Rican Embassy, where the former lawmaker had earlier sought political asylum after the attorney general's office ordered him arrested on charges he conspired with militia commanders.

The arrest edges the "para political" scandal closer to President Uribe as he fends off concerns about congressional stability with more than 60 lawmakers under investigation and half of those behind bars for suspected paramilitary links. "The arrest warrant for Sen Mario Uribe hurts me, but it is a pain I will accept with patriotism and without avoiding the fulfillment of my responsibilities," the president said in a brief statement before his cousin's arrest.

Outstanding warrant

The ex-senator had earlier asked for political asylum in the embassy, but San Jose rejected the petition as "inappropriate" because he had an outstanding warrant.

Alvaro Uribe, a close US partner, has reduced violence from Colombia's four-decades-long conflict by driving back rebels and negotiating the surrender of illegal paramilitaries who massacred peasants and dealt in cocaine in the name of counter-insurgency.

Foreign investment is growing and the economy booming. But the president has struggled recently to convince US Democrats to back a free trade deal as US lawmakers and rights groups worry over paramilitary violence.