Colombia's government is seeking to ward off a political scandal after the police revealed their intelligence agents had illegally wiretapped state officials, opposition figures and journalists for years.
The incident was a new blow to Alvaro Uribe, the Colombian president and a key Washington ally.
Uribe on Monday was forced to replace his national police commander and the police intelligence chief who, along with ministers, said they were unaware of the agents' clandestine operations.
Angry opposition
Carlos Gaviria, a leader of the Alternative Democratic Pole opposition party who officials had been bugged, said: "Someone must respond for this politically.
"It is not possible that a democratic government uses military and police intelligence to pursue its opposition."
Gaviria told Reuters that opposition leaders could call ministers to testify before congress to evaluate how senior government officials were left in the dark about espionage by their own security services.
But Juan Manuel Santos, the defence minister, said Uribe and his commanders were also unaware of the bugging and sought to ease opposition fears they were targets of a campaign.
"Neither he, nor I, nor the government had any idea this was happening," Santos said.
"This was not just against the opposition ... there were interceptions of government people, the opposition, journalists, in fact, a broad range of people."
'Para' scandal
Uribe has received millions in US aid to help quell a four-decade-old conflict fuelled by drug trafficking. He has negotiated the disarming of 31,000 paramilitaries and jailed their commanders under a peace deal handing them short prison terms for giving up theirs guns and confessing to crimes.
But he is under fire from critics since 13 congress members and more former politicians were arrested on charges they colluded with the paramilitary leaders before the peace deal when the militias controlled large areas of Colombia.
Rights groups say the "para" scandal is unearthing the depths of paramilitary influence, but Uribe says the arrests prove that Colombian justice works and denies any links himself to the paramilitaries.