More than 1,000 antiabortion activists, told by their leaders that they are engaged in a "life and death" struggle to stop the killing of unborn babies, rallied in Alexandria last night to prepare for protests at clinics today and tomorrow across the Washington area.

At the same time, abortion rights groups said they have set in motion elaborate plans aimed at keeping clinics open.

Randall Terry, founder of Operation Rescue, told the antiabortion activists gathered at Del Ray Baptist Church last night, "We are at war. We are in a life and death war for the future . . . . This is literally a fight to the finish. It's a winner-take-all situation."

The activists, from as far away as Washington state, planned to gather at 6 this morning at the Planned Parenthood office near the corner of 17th and Q streets NW, according to Susan Odom, an organizer of the event, called D.C. Project II.

Odom said it was uncertain whether a "rescue" effort would take place at the center. Operation Rescue, which has favored a style of protest in which followers block access to clinics, routinely keeps the sites of its blockades secret until the last minute.

Terry said in an interview before the rally that any demonstrations would be peaceful. "We must repent for the child killing . . . by peacefully placing our bodies on the line," Terry said. "We will not stop saving children."

Last night's three-hour rally of prayer, song and speeches drew a range of followers, from young children to the elderly; garb ranged from expensive suits to tattered jeans.

Rallies also are scheduled for 7:30 tonight at St. Bernard's Church and School in Riverdale and tomorrow night at Riverdale Baptist Church in Upper Marlboro.

Marci Wasserman, a volunteer with the pro-choice Washington Area Clinic Defense Task Force, said yesterday that at least 200 members will assemble at 5 a.m. today and 500 members will gather tomorrow morning in locations in Falls Church, downtown Washington and Silver Spring.

Wasserman said groups will be dispatched to keep open "rescue" sites as soon as their locations are learned.

"For us, the bottom line is the women and the patients," Wasserman said. "Women have a right to go unhindered into reproductive health clinics and see their doctor."

Wasserman added that she supports free speech and the right of antiabortion groups to protest, but that groups such as Operation Rescue have violated others' rights.

"These people don't care about free speech and they don't care about women's rights," Wasserman said. "All they want to do is deny these women their right to free choice. A lot of these women are not even going to the clinics for abortion-related treatment."

In the past year, federal judges in the area have granted injunctions sought by the National Organization for Women barring antiabortion groups from blockading clinics.

Among the injunctions was one issued here by U.S. District Judge Louis F. Oberdorfer forbidding any blockades at District clinics.

Yesterday, Oberdorfer vacated an Oct. 4 order that was aimed at preventing Operation Rescue from hiding assets behind the names of new organizations or individual donors.