Reacting to pressure from a key U.S. senator, the D.C. City Council last night adopted emergency legislation designed to make it easier for prosecutors to keep offenders who repeatedly commit violent crimes in jail until their trials.

The measure passed by voice vote after some council members complained about Capitol Hill involvement, while others declared that it will probably not be as useful a crime prevention tool as its promoters suggest.

The bill, in effect a revision of current D.C. bail laws, will allow prosecutors in some cases to hold repeat offenders for up to 90 days before they come to trial--an increase of 30 days over present law. It was proposed Monday by Mayor Marion Barry, 10 days after Sen. Alfonse D'Amato (R-N.Y.), chairman of the Senate subcommittee on D.C. appropriations, said that the city should do something about what he called "the revolving door of justice" here.

"This will make some, perhaps minor, improvements," council member Betty Ann Kane (D-At Large) said last night, "but we should not expect to see . . . a dramatic drop" in crime.

Jerry A. Moore (R-At Large) announced that he was voting for the measure only as "a public accommodation to . . . Mr. D'Amato who has control over our financial destiny."

John Ray (D-At Large) said the council, which turned down similar legislation offered a year ago by council member David A. Clarke (D-Ward 1), was acting only after Barry and Council Chairman Arrington Dixon "ran back down here with their tails between their legs" after meeting with D'Amato.

Stanley S. Harris, U.S. Attorney for the District of Columbia, told the council last night that the law revision would give prosecutors greater leeway in keeping the most dangerous offenders in jail. However, he said, the measure's 90-day detention provision probably would affect fewer than 100 cases a year.

Harris said that his office sought to hold 33 suspects on pretrial detention during all of last year and only 11 so far this year."We're not talking about great numbers," he said.

As emergency legislation, the bill will go into effect for 90 days after Barry signs it. The council also gave initial approval to identical permanent legislation, which must be voted on again and is subject to a 30-day review period by Congress before it becomes law.

In addition to the 90-day hold provision, the emergency bill would extend from five calendar days to five working days the amount of time prosecutors could hold suspects to determine whether they have violated parole or probation restrictions.

It also establishes a three-day hold for suspects who are out on bail on previous offenses but who haven't been brought to trial to determine whether the previous bail should be revoked, and allows judges to inquire into a suspect's source of bail money or other securities to determine whether they stem from illegal sources.

In other actions, the council gave final approval to a bill that extends liquor store hours, allows credit card liquor sales and limits the number of chain convenience store outlets that may hold beer and wine licenses, and passed other measures that revise the city's laws against theft and other white collar crimes, and allow the public school system to lease space in vacant school buildings and use the funds for education improvements.