Mayor Marion Barry asked the City Council yesterday for special emergency powers that would allow him to supersede the school board and bargain directly with the Washington Teachers' Union to end the teachers' 18-day stricke.

Responding to Barry's request and his invitation to a new round of negotiations, representatives of the union and the school board gathered last night att he Hotel Washington, along with the mayor and other top city officials, to start what they said would be round-the-clock negotiations.

Under pressure from the mayor, members of the school board also came to the hotel. They said they would remain in a room close to the negotiations, but would not take part directly in the talks themselves as union leaders had demanded.

After a long dinner, paid for by the city government, the parties gathered in separate meeting rooms on the hotel mezzanine about 11:15 p.m.

The actual talks began about 12:15 a.m, folloring a dispute over which rooms were to be used by the parties for privatre caucuses and the negotiations.

"The board members decided to come because we are interested in getting the schools opened again," said board president Minnie S. Woodson during the dinner in the hotel dining room before the talks began. "We will be nearby to give consultation and guidance to our negotiators, but we're not going to do the negotiating ourselves."

Union president William Simons, who ate at the other end of the dining room told reporters "I have no feelings whatsoever" about the new round of talks. Earlier the union had pressed for board members to become directly involved in negotiations.

Barry made his request for emergency powers late yesterday in a press conference for which he asked and received live television coverage.

Describing the strike and stalled negotiations as a "crisis," Barry said he was forced to make a "last ditch effort" to end the first major confrontation to face his administration.

"If the school system was an island in itself and could do anything it wanted to do, I would not be sitting up here," Barry said at an early evening press conference. "It's not an island unto itself. This is becoming a governmental crisis."

Since the strike began March 6, Barry said, half the city's public school students have stayed out of school and those in attendance have been in overcrowded classrooms. Juvenile arrests have increased by 49 percent, he said, and there are 12,000 children each day on city kplaygrounds during school hours.

"The strike has already lasted two weeks and a resolution between the parties appears to be less likely each day the strike continues," Barry said. "I am very concerned about the possibility that other unions may become involved in this labor dispute."

Barry did not set a deadline by which he hoped the union and school board must reach an agreement to avoid his entry into the negotiations. The proposed legislation, which is supported by City Council Chairman Arrington Dixon, is not expected to be voted on until Tuesday.

"This is a last ditch effort to try to get a settlement by this weekend," Barry said. "I believe honestly that the two parties, if they sit long enough and dig deep enough, can come to an agreement.

"The only way they can stop me from askinsg the Council to pass this legislation is to end the strike, Barry said.

The mayor's proposal was immediately criticized by the president of the school board, which has jealously guarded the authority it is given in the cityhs charter to settle disputes with teachers.

The board has also staunchly opposed intervention by the mayor because Barry's campaign was endorsed by the teacher's union and in the past, board members say, intervention by the mayor's office has worked to the union's benefit.

"I'm puzzled again," said Board Presient Minnie S. Woodson, "Why in haven's name he's intervening now, I don't know. He say's there's crisis situation. There's been a crisis situation for the last 11 months, We've said that."

"Maybe this is what they (the union) want," Woodson said. "It was their strategy before, and it's been union strategy in other cities."

The Barry plan also drew immediate opposition from City Council member Betty Ann Kane (D-at large), a former school board member. "That's a dangerous precedent," Kane said, "I don't think we have to set a precedent where every time there is a strike or a threat of a strike an elected official from another branch comes in on an emergency basis and raises hopes that it will be settled quickly."

The legislation proposed by Barry yesterday would amend the city's mewly/enacted merit personnel law. It would allow Barry to negotiate an interim agreement with the union which, if approved by the City Council, would be binding on the school board until a permanent agreement is reached.

The legislation would not allow the terms of the interim agreement to exceed the terms of the expired contract and would stictly forbid inclusion in the temporary pact any increases or decreases in pay.

Barry proposed that the legislation be enacted on a 90-day emergency bais. Under such an enactment, eight Council votes would be necessary to declare an emergency and seven votes requried to pass the legislation, if all 12 council members were present.

Although the congressionally enacted city charter vested "control of the public schools" in the school board, it assigned broad powers over personnel administration to the mayor.

Barry said the provision was checked "by the best legal minds" to assure that it would not breach the school board's power over the schols.

Earlier yesterday, negotiations remained deadlocked even though representatives for both sides arrived at the headquarters of the Federal Mediation Service at 10 a.m.

Since the strike began March 6, the teachers union has not retreated from its initial position that its members will return to work only if its former contract is fully reinstated.

Early yesterday afternoon the board negotiators repeated their offer to extend major portions of the old contract on an interim basis while a fact-finding panel makes recommendations to settle long-term contract issues.

The board added one more section, relief from nonteaching duties, in addition to provisions dealing with grievances, teacher discipline, and involuntary transfers which it had offered to extend earlier.

But the new board propsal still would not extend contract provisions dealing with grades, student discipline, the union dues check off and union power over policy-making.

It includes no promises abvout make-up work.

The proposal says no teacher will be punished just for participating in the strike but says the board "reserves the right to take disciplinary action" against strikers found guilty of violence or intimidation.

Yesterday morning Simons told reporters that the proportion of teachers taking part in the strike had declined to about 70 to 75 percent. Earlier in the week the union had estimated that more than 80 percent of all teachers were away from work.

The school board has been reporting a small but steady increase in the proportion of teachers coming to work. Yesterday it said 48 percent of the city's more than 6,000 teachers were in their classrooms along with about 49 percent of their 113,000 students.

About 1,200 teachers attended a union rally at the Greater New Hope Baptist Church. They gave Simons a warm ovation, and also heard instructions on how to apply for food stamps and union loans.

The teachers union pays no strike benefits.

Washington Post Staff Writers Juan Williams and Jack Eixsen contributed to this story .