BONN, JUNE 15 -- A West German Navy support vessel, observing target practice during a Warsaw Pact naval exercise in the Baltic Sea, was accidentally struck today by artillery rounds fired by one or more East Bloc ships, the Defense Ministry said.

Shrapnel injured three sailors, none critically. The government said it would study the incident, the first of its kind since World War II, before deciding to protest.

"We regard this incident with great composure, as we believe that it was caused by either human or technical error," Defense Ministry spokesman Capt. Ulrich Hundt said.

The Warsaw Pact had issued a warning for today and Tuesday that its ships would be engaged in a shooting exercise in the area where the ship, the Neckar, was hit, West German radio reported.

The Neckar, a depot ship on routine assignment to monitor the Warsaw Pact exercise, was struck by four rounds on the side and one in the rear, Hundt said. A fire broke out and the ship took on water, but the crew quickly extinguished the blaze and repaired the leaks, he added.

When it was hit this morning, the Neckar was cruising in international waters about 25 nautical miles from the Soviet coast, in the southeastern corner of the Baltic, the ministry said.

One of two Polish corvettes was believed to have hit the Neckar with 30-mm rounds, Defense Ministry sources said. An East German corvette also was in the area, they said.

The East Bloc ships were firing artillery rounds at pilotless drones to practice shooting down incoming missiles, the Defense Ministry said. Some of these rounds struck the Neckar, which was ordered to return to its home port of Kiel.