An alleged drug smuggling ring sold an estimated $250,000 worth of illegal cocaine weekly for at least a year to Washington-area customers, an undercover police detective told an Alexandria jury yesterday.

District of Columbia Det. Michael E. Hubbard, appearing as federal prosecutors' star witness, detailed his role in a year-long police investigation of the alleged ring, described by prosecutors as a major East Coast operation.

Hubbard's testimony and wiretaps played in court of Hubbard arranging drug deals by telephone with accused membnrs of the ring came during yesterday's opening day of the trial of five defendants in U.S. District Court.

Prosecutors, who called the alleged ring one of the biggest ever in the metropolitan area, siad the case involves the purchase and seizure of more than $500,000 in drugs and cash during the undercover probe. The investigation ended with two raids on fasionable apartments in Washington's Virginia suburbs last May.

Hubbard, who worked with federal drug agents, has said in court documents he purchased cocaine from the defendants on numerous occasions.

Hubbard testified that in order to win the defedants' confidence, he created for himself the role of a Philadelphia pornography dealer named "michael Lewis" who wanted to branch out into cocaine distribution.

Hubbard told the jury of nine men and three woman yesterday that defedant Michael F. Tillery had given him the $250,000 figure, in explaining why it was difficult to find enough high-quality cocaine to satisfy "lewis'" needs.

The quater-million dollar figure reprnsented street sales of five kilos, or 11 pounds, of cocaine which was regularly sold to customers in the metropolitan area, Hubbard testified he had been told by Tillery. The cocaine, which commonly sorted thuough the nose in small amounts, was supplied to the alleged ring by an otherwise unidentified "Big Man," Hubbard told the jury.

The "Big Man," Hubbard told the jury.

The "Big Man" supplied the five kilos of cocaine to the alleged ring every week to 10 days, and the drugs were allegedly sold on the street within 48 hours after receipt, Hubbard testified he had been told.

Tillery, and defendants Wayne McNair Hargrove, Marian Teresa Addair Starr, William Barry Robinson, and Paulette Ashton have pleaded innocent to the charges.

Opening arguments were muted on both sides yesterday, but defense attorneys immediately attacked Hubbard's credibility after he had spent nearly six hours on the witness stand.

Attorney R. Kenneth Mundy, representing Hargrove, bluntly told the beared police officer that he "could not" have met Hargrove in a police cell shortly after Hargrove's arrest because Hargrove was in another location at the time.

Hubbard insisted that he had met Hargrove, and said he recognized him by his voice, wich he had been listening to during 29 days of court-approved wire tapes on apartments frequented By Hargrove and others.

However, Hubbard agreed that there was no official record of his visit to the cell, which he said he had made with another officer.

Attorney Thomas Bepko. representing Starr, asked Hubbard if he had ever had sex with Starr, offered her $900 in "living expenses," or offered to set her up in her own business. Hubbard denied each statement.

Assistant U.S. Attorney Nash Scott introduced as evidence nearly one dozen envelopes od cocaine, which Hubbard testified he had purchased from the defedants. The purchases were made in parked car at National Airport, a room at the Hospitality House hotel in Arlington and elsewhere, Hubbard testified.

Also introduced were cassette recordings of the alleged conversations made on phones in the apartment at the Representative rented by Tillery and Hargrove.

Tillery allegedly told Hubbard that when they spoke on the phone, they should used coded language when speaking of cocaine purchases. In one example, Hubbard testified Tellery told him that mention of a "one-bedroom apartment" would indicate one kilo or cocaine, and a "two-bedroom apartment" would indicate two killos, Hubbard said.

Hubbard testified he told defedants he was unable to snort cocaine with them because he has "high-blood pressure." When this led Tillery to suspect he was a policeman, Hubbard testified he dissuaded Tillery during dinner at the Windjammer Resaurant in Arlington.

Eleven people were originally indicted. Charges against two have been dropped, three have pleaded gulity, and one defedant is still at large. The prosecution case aginst the remaining five is expected to finish today.

Each of the defendants is charged with conspiracy and distribution of cocaine, which carry a maximum penalty of five years in prison and a $15,000 fine for each offense.