D.C. Mayor Sharon Pratt Dixon said yesterday she will not support cuts in Metrorail service if the District and other local governments have trouble paying their transit subsidies.

The mayor, through her spokesman, Paul Costello, knocked down the suggestion made Thursday by two of the District's representatives to the Metro board. The board members said the rail system might have to cut service by extending the waiting time between trains.

In the budget year that starts July 1, Metro officials have proposed a 3 percent increase in the contributions from local governments.

Fares alone don't cover costs, so the governments make up the difference through subsidies.

"It's going to be very difficult, in light of the District's dire fiscal situation, to meet the increase in subsidy," Costello said. "But Metro service should not be compromised."

The District pays the largest subsidy -- about $117 million this year -- and has had difficulty making its quarterly payments. The D.C. government is planning layoffs, service cuts and reductions in other programs to meet a projected $300 million budget deficit.

At a meeting of the Metro budget committee Thursday, board member Gladys W. Mack of the District raised the possibility that if Metro does not collect enough money from expected fare increases and from the local government subsidies, the rail system might have to lengthen the time between train arrivals at stations.

Trains now arrive about every three minutes at the busiest stations during rush hour.

Longer times between trains would lead to more crowded platforms and trains, Metro officials said.

At the meeting, Mack told her fellow board members, "I don't think we have the luxury anymore of sitting here and saying, 'Here's the bill we'll send to local jurisdictions' " and they will pay it.

"If the District gets a big bill for Metro, they may send it back to us and say, 'Take it out of service, because the money isn't there,' " she said.

Another board member from the District, Matthew S. Watson, said Thursday that it would be hard for the D.C. government to order major cuts in dozens of city programs, as is planned, without asking the Metro system to do the same. He said fare increases and service reductions would be necessary to keep the local government subsidies from rising.

Costello said yesterday that the mayor will not advocate that approach, though he said it was too early in the budget process to say how the D.C. government will meet the planned 3 percent increase. Fares probably are going to rise July 1, by about 18 percent.

Mack said yesterday that her Thursday comments were misinterpreted and stressed that she did not want to appear to be feuding in public with the mayor.

She said the board can find more money by raising fares, increasing the subsidies and cutting costs.

In cutting costs, she predicted yesterday, the transit agency would attempt to avoid cuts in service.

The possibility of slashing service is a sensitive subject for board members, who in Metrorail's 14 years of operation never have had to make such cuts.

Mack was appointed by Mayor Marion Barry and now serves at Dixon's pleasure.

Board Chairman Mary Margaret Whipple, of Arlington, said she understood Mack to say that if fares are not raised substantially and the local governments are unable to pay the 3 percent subsidy increase, cuts in service are possible.