Restaurateur Hassan H. Mohammadi testified yesterday that he supplied D.C. Mayor Marion Barry with cocaine "about 30 times, maybe more," and he rolled up a dollar bill to show the jury how he said he and the mayor used one to snort cocaine.

Mohammadi told the jury in Barry's drug conspiracy and perjury trial that he and the mayor used cocaine at Mohammadi's Georgetown restaurant, at his 31st Street NW apartment, at another Northwest Washington home and at a luxurious hotel in the Bahamas.

He said he first saw the mayor use cocaine at the February 1985 opening of his former restaurant, Pardis Cafe, when Barry went upstairs to Mohammadi's office to snort it with nightclub manager Sammad Arshadi.

"Arshadi brought the folded {dollar} bill, and he would take out some of the powder and he put it on the desk, and he made a line with {a} credit card . . . and they snorted," Mohammadi said.

That 1985 episode represents the earliest allegation of drug use for which evidence has been presented so far in the trial.

The indictment alleges that Barry was involved in drugs as early as 1984.

Mohammadi brings to four the number of witnesses in the five-week-old trial who say they saw Barry use drugs, and he is the second to testify that he delivered drugs to Barry at his office.

Another witness, Lydia R. Pearson, who testified that she delivered crack cocaine to Barry at the Reeves Municipal Center at 14th and U streets NW, ended her testimony earlier yesterday.

Mohammadi is the first witness to address the count in the indictment charging that Barry possessed drugs in November 1987. So far, the government has presented evidence on seven of the 10 possession charges.

Mohammadi testified under a plea agreement with federal prosecutors. On May 29, he pleaded guilty to conspiracy to possess cocaine before U.S. District Judge Thomas Penfield Jackson. He is awaiting sentencing.

Mohammadi testified yesterday that in return for his testimony about the mayor the government will recommend leniency for the charge to which he has pleaded guilty, ask the Immigration and Naturalization Service not to deport him to Iran and not seek additional charges against him.

In addition, he said the government agreed not to freeze his assets. He did not explain the government's interest in his money.

Arshadi once managed sexually oriented nightclubs on 14th Street NW, including This is It? and Butterfly. The first published reports of allegations of drug use by Barry, in 1983, centered around the This is It? club. More recently, Arshadi has managed a restaurant on Wisconsin Avenue NW.

Mohammadi testified yesterday that he met Barry in 1984 at a party held for the D.C. delegation to the Democratic National Convention, and got to know him better after opening the Pardis Cafe the next year.

After the restaurant's opening, Mohammadi testified, he became friendly with a friend of the mayor's, Charles Mason. Mason is married to Ann Simpson-Mason, a senior Barry administration official.

Mohammadi said he frequently gave Mason loans for which he did not expect repayment, and let Mason eat and drink at the Pardis Cafe without charge. When Mohammadi had a problem with a $4,500 water bill from the city, he said, Mason, an official at the D.C. Public Works Department, arranged for him to pay it in installments of $200.

At a bench conference after this testimony, defense lawyer Robert W. Mance asked Jackson to forbid any testimony about "contracts" or "improprieties." Roberts said he would avoid those areas.

In February or March 1987, Mohammadi said, Barry made his first visit to Mohammadi's apartment on 31st Street NW. Arshadi arrived shortly afterward, he said, bringing cocaine in a folded dollar bill.

Barry asked him where the bathroom was, Mohammadi testified, and the two men went there. He said Barry took the cocaine and used a dollar bill to snort it off the bathroom counter.

Barry, appearing last night on the "Insight" talk show on radio station WHUR, said the government's witnesses were testifying against him only to save themselves. "Basically, what the government has done is find people, some of whom were friends or associates of mine, who have a lot to lose," Barry said. The witnesses, he added, were "engaged in activities that could be criminal, or could be charged, or they face deportation or other kinds of strenuous kinds of consequences. And they paraded them out."

Like other witnesses, Mohammadi said Barry used coded language to raise the subject of drugs.

"He did not have specific word for it -- 'I need cocaine' -- but he would say, 'What is happening?' 'Are you loaded?' you know, stuff like that," Mohammadi said.

In April 1987, Mohammadi testified, Barry made his second visit to Mohammadi's apartment. In preparation for the mayor's arrival, Mohammadi said he bought one gram of powder cocaine from Arshadi. "He asked me if I have anything, and I said, yes, I do have, and he went to the bathroom," Mohammadi said.

In the bathroom, Mohammadi said, he used a credit card to scoop cocaine from a folded dollar bill and scrape the powder into lines on the counter. Then, using a dollar bill rolled into a tube, "I gave him and he snorted . . . and I did it the same."

In November 1987, Mohammadi traveled with Barry to the Bahamas. Mohammadi said Barry asked him to bring powdered cocaine for the trip. Mohammadi said he told Barry he did not want to carry drugs across an international border for fear of being searched. Barry, he said, replied that he would have "no problem" carrying the cocaine himself.

Soon after, Mohammadi said, he placed more than two grams of cocaine in a business envelope, wrapped the envelope in a magazine and delivered the magazine to Barry in his District Building office.

On Nov. 26, Mohammadi said, he joined Barry in the Bahamas, where the two men spent time with Barry's son, Christopher; Barry friend Jeff Mitchell; Bettye Smith, then a city investment consultant; a man named "Carlos" whose last name Mohammadi never learned; and a young woman he knew only as "Miss T." Smith baby-sat with Christopher, Mohammadi said.

One evening in a casino, Mohammadi said, the mayor used $3,000 to $4,000 of Mohammadi's chips at the blackjack table.

In a hotel room, Mohammadi said, he and the mayor smoked marijuana and a cigarette containing both cocaine and marijuana that Barry called an "M.B. Special."

The next morning, Mohammadi said, "I asked him if he had a good time and he said yes, he did, he had a good time, and he said, 'She killed me.' "

"Who killed him?" Roberts asked.

"Apparently, Miss T," Mohammadi replied.

Mance said in an interview that "Miss T" was Theresa Southerland. She is a former Barry girlfriend, sources said.

On Nov. 29, preparing to leave the Bahamas, Mohammadi said Barry asked him to put Miss T's hotel room charges on Mohammadi's credit card. Mohammadi testified that Barry said a Washington Post reporter had been inquiring about the trip, and he did not want the reporter to know that "Miss T was here for Mr. Mayor."

Mohammadi rarely called Barry anything but "Mr. Mayor."

Mohammadi also testified about an October 1987 meeting with Barry at the Washington residence of Sallie Melendez, then a top aide to the mayor. Barry, Mohammadi and Melendez all snorted cocaine from a kitchen countertop, he testified.

Mohammadi testified that:

He gave drugs to Barry about 30 times.

He once delivered two grams of cocaine to Barry's office in the District Building.

He used opium with Barry.

He snorted cocaine with Barry and a top Barry aide, Sallie Melendez, at her house in Northwest Washington in 1987.