BOGOTA (Reuters) - Costa Rica on Tuesday refused to grant asylum to Colombian President Alvaro Uribe's cousin after prosecutors ordered him arrested for suspected ties to paramilitary squads in a deepening scandal for the U.S. ally.

The investigation of Mario Uribe, a longtime senator and presidential confidant, is expected to fuel concerns among U.S. Democrats who oppose a Colombian trade deal because of human rights abuses and the lingering influence of ex-paramilitary commanders.