Federal agencies are quietly building up support staffs here and overseas for operations in the Middle East. This in spite of a limited hiring freeze in most other government operations.

Hundreds of workers, mostly in Defense agencies, are being shifted to special jobs or task forces to deal with the increasingly serious Iranian situation, and others are being hired for support activities here and overseas. s

In recent weeks the Army Corps of Engineers put out a call for a "large number" of engineers and construction specialists to work in Saudi Arabia. In addition to regular federal salaries, those person will get a 20 percent pay differential, cost-of-living allowances, government housing and generous paid leave.

A lot of people are interested in the crisis-related jobs. A short item here April 8 about the Saudi Arabia jobs and about a staff buildup at the giant, super-secret "underground government" command center in Berryville, Va., brought in more than 1,000 calls from jobs seekers. (The telephone for the Saudi Arabia jobs is 554-7960, ext. 2447. For Berryville, the number is 554-7960, ext. 2174.)

Air Force and Navy also are shifting personnel and resources to Middle East support activities. The Pentagon is anticipating a major, long-term buildup. The CIA also is looking for people with language and technical expertise that would be helpful in monitoring Middle East activities.

The Military Sealift Command here is looking for marine transportation specialists with experience in operating ships. This is in anticipation of any Persian Gulf blockade and increased supplies to American bases in that area. The telephone number for those jobs is 282-2874.

While most federal offices are limited to filling only half their vacancies -- one replacement for every two vacant jobs -- Middle East-related efforts have been exempted from the freeze. Where they have not, agencies are taking slots from lower priority functions during the freeze.

Federal officials expect the hiring freeze will last another couple of months, until overall federal employment drops by 19,000 to 20,000 jobs. But that could all change rapidly if the Middle East buildup continues.