Fairfax and Arlington counties yesterday proposed a maximum 10-cent subway fare increase to take effect in January, but the two jurisdictions differed on whether bus bares should also be increased.

The Metro budget committee, which must take final action by Dec. 4 in order to put new rates into effect by Jan. 3, was stalled yesterday because only the two counties -- out of its seven member governments -- were prepared to present rate proposals. The others are expected to submit proposed rate proposals. The others are expected to submit proposed rate increases to the committee next Thursday.

While both Arlington and Fairfax agreed that peak and off-peak Metrorail fares should be increased to 60 cents, Arlington firmly opposed an increase in Metrobus fares.

"We felt that the 22-percent increase in bus bares earlier this year was enough," Arlington County Board member Dorothy Grotos said after yesterday's meeting. "Since Metrorail rates hadn't been increased this year, we felt higher rates there were appropriate."

Fairfax County proposed that the basic Metrobus fare be kept at 60 cents during both peak and non-peak hours and that river crossing and zone charges be increased a total of 35 cents. A rider using both rail and bus connections on the longest Fairfax County route would pay an additonal 73 cents a day, round trip, under the proposal.

"Some of us believe that we'll lose riders in the last zone in Fairfax if the rate increase goes through," said Fairfax County Supervisor Marie B. Travesky. "At the same time, there is no way t hat we can cut service."

General Manager Richard S. Page, who proposed in September that fares be increased 10 cents to help make up an anticipated $12 million shortage in Metro's operating budget, said yesterday be would like to see all Metro Board members agree to a standard peak-hour rate.