A unusual invitation-only public meeting inside the Central Intelligence Agency compound in McLean is scheduled tomorrow night to allow nearby residents to express their concerns about increases in traffic that will accompany a planned expansion of the facility.

More than 3,000 additional employes are to be housed in a new seven-story, $100 million building at the secluded complex. Plans for the expansion were approved last year by the National Capital Planning Commission, the region's federal planning agency, but the project has not yet been funded by Congress.

But CIA officials have said that to encourage car-pooling, only 1,000 new parking spaces will be added. They also plan to stagger working hours to help ease rush-hour traffic. Still, area residents are worried that traffic conditions will worsen.

About 600 people, including numerous local officials, have been invited to tomorrow's meeting, which was arranged by Rep. Frank R. Wolf (R-Va.). Also expected to attend are Virginia state highway engineers. They will be responsible for any changes to the main entrance to the compound off Virginia Rte. 123.

The Ad Hoc Committee on Off-Site Traffic To/From the CIA, a recently formed citizens group that claims to speak for about 1,000 homeowners living around the CIA, would like to see only minor changes on Rte. 123 and a major expansion of the agency's second entrance, on the George Washington Memorial Parkway.

The National Park Service, which owns and maintains the scenic parkway, has been working with the CIA on plans to improve one of the exit ramps that it says is dangerous, but opposes expanding the traffic-clogged parkway into a major CIA entrance, according to assistant parkway superintendent Kitty Roberts.

No designs have yet been approved for changes at either of the agency's two road entrances.

CIA spokeswoman Kathryn Riedel said Friday that state and federal highway planners will study and design the road changes and, since the CIA's area of expertise is not in highway planning, it is merely attempting to coordinate the project and ensure that citizen concerns are considered.