Mayor Marion Barry came under renewed attack from opponents in the mayoral campaign last night, this time for allowing the hiring of an official from outside the District to run the city's board of elections.

Five of the seven candidates at a forum sponsored by Waterside Baptist Church in Southwest charged that the hiring of Erie County, N.Y., elections official Teddy Filosofos was hypocritical for an administration that has urged private employers in the city to give preference to District residents when hiring because of the high rate of unemployment in the city.

"One of the biggest excuses of all the excuses made by this administration," said At-Large City Council member Betty Ann Kane, "is that they can't find qualified people living here to work in the government.

"You can't expect private industry to hire city residents if the government doesn't set the right tone," Kane said. "When they appointed Filosofos to run the elections board, they said that no one here could do the job. That added insult to the injury of the mess that has been made of our elections."

"Now Marion is a friend of mine," said Republican candidate E. Brooke Lee, "but I don't understand why he felt he had to run to Erie or some other dirty lake to get a guy who'll take years to learn this town before he can do the job."

The criticism of Barry came after the candidates were asked how they would ensure that more District residents got jobs in the many developments under way downtown.

Barry, who was joined at the forum by Democrats Kane, Ward 4 council member Charlene Drew Jarvis, publisher Dennis Sobin and physician Morris Harper, and Republicans Lee and James Champagne, was first to speak last night and had no chance to defend the hiring of Filosofos to the gathering of about 120 people.

Barry told a reporter afterward, however, that he was "pleased" with the choice of Filosofos, Democratic deputy elections commissioner of Buffalo and Erie County, N.Y., for the $50,112 job here.

"The board of elections is in such bad shape," Barry told the reporter, "that they need to hire the best talent no matter where they can find it. That's not to say there was no one in the city who could do the job, but maybe those people weren't available to take the job.

"All I am concerned about,"Barry said, "is that we have a good election in the fall and that we hire someone who can make that happen."

Only Champagne among the other candidates at the forum supported the hiring of Filosofos.

Barry also was criticized by the other candidates for allegedly not pressuring the developer of the publicly owned Waterside Mall in Southwest--leased by the city as an urban renewal site--to include a community center and more neighborhood stores in it. Half of the 20-year-old mall is used for office space for the Environmental Protection Agency.

Barry said he "disagrees" with what the developer of the mall, Charles Bressler, is doing there but said the city's contract with Bressler is too vague to allow the city to demand that the mall be used differently.

"If I had been mayor at the time the land disposition had been signed we would not have this problem," Barry said. "I'll tell you one thing--Bressler won't get any more rights to develop city-owned property."

Harper, who spoke immediately after Barry, said the mayor's response had been "another excuse."

Democratic Candidate Patricia Roberts Harris did not attend last night's forum, and At-Large City Council Member John Ray, also a Democrat, appeared just as it was ending and did not have a chance to speak. He said he had been at a fund-raiser. Harris was out of town for the weekend.

Barry, who failed to attend a scheduled head-to-head debate with Harris last week, began his five-minute presentation last night by saying he will only attend forums at which most of the eight Democratic candidates are invited so as not to allow any group to determine who among his challengers is important or unimportant.

Later Barry said his political advisors have told him not to take part in debates with any one candidate.

"Debating with Harris is a sideshow," Barry said, "like at a circus. The main event is who has demonstrated the ability to run a local government, reduce crime . . . not who is the best at debating."