A Metro board committee took the first step yesterday toward increasing subway and bus fares on July 1 when it proposed public hearings on two possible higher subway fare schedules.

One schedule would increase the basic one-way rush hour charge from 45 cents to 50 cents, the other from 45 cents to 55 cents. Both schedules include additional increases for rush-hour subway trips that exceed three miles.

The lower of two fare proposals would represent about an 11 percent increase for subway riders. The higher would represent about a 22 percent increase.

The committee postponed action on possible bus fare increases yesterday, but it is clear that the suburbs will insist on some fare increase for their riders. The District of Columbia traditionally seeks to maintain bus fares for its residents at the current level of 50 cents in rush hour and 40 cents the rest of the time.

Before a public hearing can be held, the fare proposals must be ratified by the full Metro board, but the recommendations of the board's revenue and operations committee almost always receive board endorsement.

Both Maryland and Virginia representatives on the committee proposed the higher fare schedule for subways yesterday: the District of Columbia proposed the lower. It was agreed on a 3-to-3 vote that the present 50-cent, nonrush-hour fare that has proven so popular with tourists and weekend Metro riders would be retained for at least another year. That decision could change.

Under the proposals, the rush-hour fare from Ballston to Metro Center would increase from 65 cents to either 70 cents or 80 cents. The rush-hour fare from Silver Spring to Metro Center would increase from 90 cents to either $1 or $1.10. The rush-hour fare from Stadium-Armory would increase from 50 cents to 55 cents or 60 cents, and the rush-hour fare from New Carrollton would increase from $1.15 to $1.25 or $1.40.

Metro's operating costs have been stricken with the same double-digit inflation afflicting the rest of the country, and a major fare increase to compensate is a certainty. The question is going to be over the amount. The lower fare proposal would raise an estimate $3.2 million in revenue. The higher proposal would raise an estimated $6.4 million.

Metro General Manager Richard S. Page has proposed a 41 percent increase in subway operating subsidies for the fiscal year beginning July 1. Although that proposal will doubtless be cut somewhat in the Metro budget process, the opening of a new segment of the system to Addison Road later this year plus increased emphasis on maintenance and security forces will mean some increase in costs.

A 30 percent increase is anticipated in Metro's bus operating subsidies and the total fiscal 1981 subsidy to be paid by local, state and federal governments is projected at $157.5 million.