Two prominent transportation officials called last night for new measures to finance multibillion-dollar highway and mass transit costs in the Washington area and across the nation.

Ralph L. Stanley, the Reagan administration's mass transit chief, and Ronald Kirby, a transportation analyst for the Urban Institute here, outlined their proposals at a conference of the American Planning Association. Both officials urged controversial moves to link highway and transit financing.

Stanley, who heads the federal Urban Mass Transportation Administration, cited a plan under consideration by the Reagan administration that would establish "urban mobility block grants" to help local governments pay for road and transit projects.

The federal government currently provides separate funds to localities for transit and for highways. The new proposal would combine funds for some road and transit programs in an attempt to force local governments to cut costs and improve coordination.

Under the proposal, Stanley said, Washington area officials would have to work out agreements to split funds among District of Columbia, Maryland and Virginia highway agencies and the Metro subway and bus system. In the past, highway and transit advocates have often been at odds.

Kirby, the Urban Institute's director of transportation studies, urged Washington area officials to adopt tax or other measures to provide new revenues for the Metro system and for highway projects. Such moves may prove more palatable to local politicians if roads and transit are linked, Kirby contended.

"If we bring in the road element, there are a lot more people who want roads," Kirby said.

Stanley and Kirby both warned that the Washington area faces severe shortages of transportation funds.

The Metro system's operating deficits already exceed $200 million a year. The transit agency is expected to need $2 billion more than has been authorized by Congress to complete the proposed 103-mile rail system. Local officials have proposed hundreds of millions of dollars in highway projects.

Last night's conference was the first in a series scheduled by the Washington area chapter of the planning association to assess prospects for the Metro system.