A District lawyer and former federal prosecutor admitted in court yesterday that he agreed to help store a cache of cocaine that would be sold to pay $10,000 in legal fees owed him by a client in a drug case.

Gerald R. Robbins, 43, an assistant U.S. attorney in the 1970s and a criminal defense lawyer locally for 15 years, pleaded guilty in U.S. District Court in Alexandria to using a phone to facilitate a drug transaction, which sources said involved eight kilograms of cocaine worth about $280,000 wholesale.

The plea by Robbins, a Georgetown Law Center graduate, stemmed from a cocaine distribution case in which his client turned on him, becoming a confidential informant for the FBI in an effort to win leniency from prosecutors, according to Robbins's written account filed in court.

Robbins shook visibly and leaned heavily on a lectern during yesterday's proceedings, telling U.S. District Judge James C. Cacheris, "I'm extremely nervous."

"Any time you want to take a break, just tell me and we'll try to give you time to collect your thoughts," Cacheris told Robbins.

An Arlington resident, Robbins could be sentenced to up to four years in prison and $30,000 in fines. He also is required to notify the D.C. Court of Appeals of his felony conviction.

Thomas E. Flynn, counsel for the District of Columbia Bar, said Robbins will be suspended when the appeals court receives the notice and may be disbarred. Flynn said 20 of the bar's 54,000 members have been disbarred in the last three years, and he could remember only "one or two" cases involving drugs.

Robbins, a member of the D.C. Bar since 1971, served as an assistant U.S. attorney from March 1972 through May 1975, according to Judy Smith, spokeswoman for the U.S. Attorney's Office in the District. Smith said Robbins handled misdemeanors and cases such as prisoner petitions.

Robert Werdig Jr., Robbins's law partner for several years until late 1987, said he was stunned by Robbins's admissions.

"I worked with the man for 10 years and there were no problems. He was damned good," Werdig said, adding that Robbins handled a wide variety of criminal and civil cases during their association.

Werdig also said he and Robbins were jointly representing clients accused in a drug conspiracy case in the District. "We were talking about this case and it wasn't too long ago . . . a week or two ago," Werdig said.

Robbins said in court papers filed yesterday that he became involved in the cocaine deal to "increase the likelihood that he would actually obtain payment" of $10,000 in legal fees and receive a $20,000 loan. Last Saturday, Robbins arranged with the client's wife to store cocaine she was bringing into the area, he said.

"Gerald Robbins understood that {the client's wife} was coming to the Alexandria area with a significant amount of cocaine and large amounts of cash," Assistant U.S. Attorney Debra S. Straus told the court.

Robbins also reserved a rental car and obtained a lock to be used in the transportation and storage of the drug shipment, court papers said.

On Monday, Robbins drove to a hotel where he met an undercover FBI agent posing as his client's wife, the plea stated. "They discussed the payment of money and the storage of the cocaine," Straus said.

Robbins was arrested in the hotel parking lot as he and the undercover agent were preparing to go to the storage site Robbins had arranged. Law enforcement sources said Robbins never took possession of the cocaine.

Robbins's client sought to become an FBI informant after he was arrested and Robbins was appointed as his attorney by the court, sources said. The client, whose name was not released, subsequently pleaded guilty to one drug count, according to the sources.

Defendants in drug-related cases commonly cooperate in other prosecutions in hopes of reducing their prison time.

Ed Wilhite, Robbins's attorney, declined to comment on the case, except to say, "This is not a big case."

The judge released Robbins after he promised to appear for sentencing Oct. 12.