Metro officials, under pressure from local governments to hold down rising costs, reluctantly opened a regional can of worms yesterday by discussing the possibility of raising rail fares.

The Metro board's budget committee asked the staff to assess the effect on ridership of raising midday and evening (off-peak) rail fares to the same level as rush-hour or peak rates.

Such a change would increase the fare for the longest rail trip on the system to $2.40 all day from the current maximum off-peak level of $1.10.

The lower off-peak rates would continue in effect for weekends along with the minimum fare of 80 cents for short rides.

No bus fare changes were proposed, but that complex fare structure, in which charges vary from jurisdiction to jurisdiction, also could be discussed if the rail issue is formally opened.

The request represented the first crack in the Metro board's resistance to raising fares, which have not increased in four years.

"I see great reluctance to look at this issue," said Gladys W. Mack, a Metro board member representing the District of Columbia. "But it's our responsibility to look at a variety of ways to fund this budget." Mack proposed the analysis of higher off-peak rail prices.

"I haven't supported a fare increase, but I do think we have to take a look at the options," said Joseph Alexander, a Metro board member and Fairfax County supervisor.

The fare discussion erupted as the board's budget committee considered a proposal to start rail service on weekdays at 5 a.m., an hour earlier. The cost of that action would be $2 million in additional subsidies from local and state governments.

Unfortunately for early birds, the proposal comes as the committee is reviewing Metro General Manager Carmen E. Turner's proposed budget for the fiscal year starting July 1. Her proposal asked local jurisdictions to contribute $257.3 million in subsidies, or $22.1 million more than they did this year.

The budget committee yesterday approved Turner's recommendation to reduce the subsidy bill by $10 million through a variety of cuts, but some board members were unsatisfied. "All this does is slow down the rate of increase" in the subsidies, said Robert B. Ostrum, representing Prince George's County.

Metro could hold fares steady for a fifth consecutive year only if it receives the higher subsidies or cuts service. The total proposed Metro operating budget is $548.3 million, an 8.3 percent increase over this year's.

Turner argued in December that the stable fares would build Metro ridership, and help alleviate the region's growing traffic problem.

The transit industry estimates that every 1 percent increase in fares causes a 0.4 percent drop in ridership, said Metro's Beverly Silverberg. For example, a decision to raise off-peak fares to the peak levels would generate $7 million a year in additional revenue, but Metro would lose riders making 4 million trips a year, according to Metro staff estimates.

Some transit specialists argue, however, that a policy of holding down fares in the face of rising costs either shifts the financial burden from the rider to the general taxpayer or results in reduced transit system maintenance.

"Our jurisdiction is not at all pleased with the subsidy level as it now stands," Ostrum said.

"The no fare increase in five years is beginning to be viewed as a policy issue in a number of the jurisdictions," Fairfax County Executive J. Hamilton Lambert wrote last week in a note to Turner. Hamilton is a member of a committee of local government officials. It has recommended that a modest fare increase be evaluated.