D.C. police rounded up 23 suspected drug buyers and sellers who chose yesterday afternoon to do business at the corner of Wheller Road and Varney Street SE -- one of far Southeast's more active narcotics marketplaces, according to police.

In most cases, the arrests were made moments after the alleged transactions, as part of a 7th District undercover operation involving hidden observation posts from which police photographed transactions and then radioed desriptions of participants to arrest teams waiting a few blocks away.

Eighteen suspected buyers were arrested yesterday, all of them in cars and most on possession of marijuana charges. Five accused sellers also were arrested, and face charges of marijuana possession with intent to distribute. All are misdemeanors.

The arrests themselves were photographed for the first time since the operation began in January, but not by police cameras. Television news crews were invited to view the operation by 7th District officials, who hope the publicity will help achieve the operation's goal -- to keep buyers out of the area by making it known that they run a high risk of arrest.

"It's supply and demand out there, just like any other business," said 7th District Deputy Chief James K. Kelly. "We're hoping to encourage the buyers to stay out of our area. We've found through experience that once a marketplace is established somewhere, that no matter what you do, if there is still a general belief among buyers that the marketplace still exists, then people will still come into it."

The U.S. Attorney's office is cooperating in the effort, Kelly said, by promising to prosecute anyone arrested in the operation, no matter how small the amount of drugs involved.

Most of the arrests yesterday -- the 7th District's fourth such operation -- involved no more than a single "nickel" ($5) bag of marijuana. Police said previous efforts in the 7th, which involved as many as 50 officers at a time and required from two to six hours to complete, have resulted in nearly 400 arrests, retrieval of an estimated $200,000 worth of marijuana, cocaine, heroin, Preludin and other narcotics, and the confiscation of 22 handguns.

"If all we did was make it clear to everyone that that's our street, our corner, as much as it is theirs, this would be worth it," said casual-clothes commander Lt. Ray Tarasovic as he crossed Mississippi Avenue at Wheeler Road SE, one of three arrest sites, and turned his outspread arms toward the crowd of onlookers attracted by the police cars and cameras.

"Back to the curb please, folks, thank you."