A secretary to Peter B. Bensinger, director of the Federal Drug Enforcement Administration, has been placed on administrative leave after D.C. police said a small quantity of suspected narcotics -- marijuana and some pills -- was found in a search of her Southeast Washington home.

The secretary, one of three who work directly for Bensinger and his top assistant at DEA headquarters here, was identified as Joan S. Jackson, 37, of 1213 Talbert St. SE. A DEA spokesman said she informed the agency of the search results on May 31, and was placed on leave that day pending an internal DEA investigation.

The search of the Jackson home was part of a continuing investigation into alleged drug traffic in the Talbert Street SE area, police said last night. The investigation has included purchases of drugs by undercover police agents, they added.

A police official in the 7th District confirmed last night that the search had been executed, and said an arrest warrant has since been issued for Jackson and her husband, James Jackson. The arrest warrant, charging a violation of the National Firearms Act on the basis of the presence of a handgun supposedly found in the apartment, has not been served pending a hearing in the U.S. attorney's office.

Neither of the Jacksons could be reached for comment.

A DEA spokesman said Joan Jackson informed the agency that she found the results of the search warrant tacked to her door when she returned from a vacation on May 31. It alledged that a "small quantity of marijuana and pills" had been found in the residence, she told her employers.

She was placed on leave that day by one of Bensinger's assistants, the DEA spokesman added.

Jackson began working as a government secretary in 1962 with the Coast Guard, and transferred to the Justice Department the next year. From 1967-74 she worked in the office of the attorney general.

She transferred to DEA in 1974 and worked directly for three administrators since then, the DEA spokesman said.

The spokesman said the agency has strict internal rules warning employes about being associated with drug use or drug users.