Colombia admits army infiltrated

His admission confirms the suspicions of many Colombians, correspondents say.

Colombia remains the biggest exporter of cocaine despite billions of dollars in mainly military aid from the US.

Mr Santos told reporters that there were indications the security forces had been infiltrated at a very high level.

"But the important thing is that we have detected this and are doing our utmost to continue the investigation and bring those responsible to justice," Mr Santos said.

Mr Santos's comments come after two incidents pointed to serious leaks in the security forces.

Classified files

The first was the arrest of a senior defence department official for allegedly passing information to the powerful Norte del Valle drug cartel.

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