WASHINGTON (AP) _ The Justice Department sought civil damages Wednesday from four anti-abortion protesters accused of blocking the only abortion clinic in North Dakota and stalking its employees.

The government's lawsuit, which also seeks a restraining order, was its fourth civil action filed under the Freedom of Access to Clinic Entrances Act of 1994 _ all within the last two months.

Citing the earlier lawsuits, Attorney General Janet Reno had warned on Tuesday that ``those who directly preach murder and violence'' are under ``intensely active investigation.''

Shortly after two women were killed at suburban Boston clinics in December, Associate Attorney General John Schmidt predicted more use of civil suits against those who threaten clinics. A federal grand jury has been looking into any links between anti-abortion violence.

The three men and one woman named in Wednesday's suit were accused of harassing the Fargo Women's Health Organization Inc. and violating local court orders issued in 1991 and 1992 to refrain them from blocking the clinic or the homes of its staff.

The suit was filed in U.S. District Court in Fargo.

The government sought an order barring the four and unnamed associates from coming within 200 feet of the clinic, its employees or their family members. It also sought damages of $5,000 for each person harassed and civil penalties of up to $10,000 apiece for first violations of the clinic-access law.

Timothy Lindgren of Moorhead, Minn.; Ronald D. Shaw of Bismarck, N.D.; and John B. Brennan and Kathy Kirkeby, both of Fargo, were named in the federal complaint.

Two weeks ago, the Justice Department obtained a court order barring Regina Dinwiddie from coming within 500 feet of a clinic she had threatened in Kansas City. A day earlier, it asked a court to stop Alan M. Smith from threatening an Ohio abortion doctor Smith had allegedly run off the road.

Last month, the department entered a private civil suit under the clinic-access law against eight people accused of blocking entrance to a Milwaukee clinic.

Criminal convictions under the law have been obtained against Paul Hill for killing a Pensacola, Fla., abortion doctor and against six of the people named in the Milwaukee suit.