Acting on intelligence input, a trap was laid and the havaldar was held in Thiruvananthapuram in April this year and handed over to the Army for further action, official sources said.
They said certain classified documents and pen drives, among other things, were seized from the possession of the staffer, identified as Sivadasan.
"The DRI had got intelligence that a staffer working with Military Intelligence was trying to negotiate a deal for passing on classified information. The input was shared with the Army officials and a trap was laid. Following which the staffer was held in Thiruvananthapuram," a senior DRI official, who did not wish to be identified said.
He said the Army officials were informed as DRI did not have relevant powers to arrest a person in the matter.
As per its charter, DRI is responsible for collection of intelligence about smuggling of contraband goods, narcotics and under-invoicing through sources in India and abroad, analysis and dissemination of such intelligence and to refer cases registered under the Customs Act to the Income Tax Department for action under the Income Tax Act.
Besides it takes action under relevant sections of the Customs Act and Narcotic Drugs and Psychotropic Substance (NDPS) Act.
Army sources said the havaldar has been detained and a Court of Inquiry (CoI) has been ordered to look into the allegations against him.