An alliance of "progressive" civic groups said Thursday that it will relocate its planned pro-unification rally this week to avoid confrontation with rival conservative activists.

The two groups scheduled separate rallies in front of Seoul's city hall for Friday, the anniversary of Korea's liberation from Japanese colonial rule in 1945.

Public concerns mounted over a potential clash between the two groups when they announced the same venue for their respective rallies.

The rival bodies are in conflict over North Korean and U.S.-related matters. Conservatives have been asking the government to strengthen American ties, while progressives accuse Washington of scheming to invade North Korea over its nuclear program.

The progressive group said they will move their rally site to Jongro, a boulevard several blocks from the city hall. They predicted a turnout of about 20,000 supporters.