West Germany's highest court ruled in favor of East Germany's former Communists on Saturday and threw out a plan for holding united German elections on Dec. 2.

The Federal Constitutional Court said the election format would deny small parties a fair chance at power in the united Germany that will be created on Wednesday.Although the ruling will not halt the historic merger, it is a victory for the now-reformed Communists who once ruled East Germany and increases the chances they will win seats in a new Parliament.

The decision also will force lawmakers to scramble this week to come up with an alternative election plan and avoid postponing the first united German elections in 60 years.

Meanwhile, the top lawman in West Berlin warned of an "alarming security situation in East Berlin," where leftist radicals have been reported to be planning riots to protest Germany unity.

West Berlin Interior Minister Erich Paetzold, in a letter to police officials in both Berlins, called on officers to work together next week to contain violence as their departments merge.

About 5,000 people marched Saturday from West Berlin to East Berlin to protest what they called "the annexation" of East Germany by West Germany.

The protest was called by a women's group demanding greater rights in a united Germany.

Although it is popularly called German unity, East Germany is essentially dissolving itself and acceding to the larger nation, whose laws will supplant East Germany's.

West German Chancellor Helmut Kohl will be in charge of a united Germany after Wednesday.

Kohl plans to add four East Germans to his Cabinet. West Germany's Parliament also will add 144 lawmakers chosen late Friday from the 400-member East German Parliament.

Among those East German lawmakers are 24 members of the reformed Communists, who are the third-largest party in East Germany but would be only a small political voice in a greater Germany.