A group of 11 antiabortion demonstrators who last month were barred indefinitely from the grounds of a Fairfax County abortion clinic by U.S. District Court Judge Albert V. Bryan Jr., have filed a countersuit against the clinic.

According to Mary Anne Kreitzer, one of the plaintiffs, the countersuit filed last week seeks an injection against the Northern Virginia Women's Medical Center to stop it from performing abortions as well as damages of $1 million for each of the estimated 16,000 abortions performed there since 1973.

Kreitzer said that the countersuit also seeks $15,000 in personal damages for each of the 11, charging the clinic's administrators with assault and battery, slander and procuring false arrest.

The charges stem from the arrests in recent months of antiabortion demonstrators who blocked the center's entrance and tried to prevent women from having abortions. The center is located at 3918 Prosperity Ave.

In the last five months, two Fairfix County General District Court judges have acquitted the demonstrators of trespassing charges. As a result, county police were directed by Commonwealth's Attorney Robert F. Horan Jr. not to arrest any more demonstrators because judges would acquit them.

Apreliminary hearing on the countersuit is scheduled for April 20.