Two Kawasaki Frontale supporters nearly caused a post-match riot by angering some Suwon Bluewings fans when they raised a controversial Japanese wartime flag in an Asian Champions League match in South Korea on Tuesday.

After Kawasaki’s 1-0 victory to Suwon in Group G, offended Suwon fans faced off with Kawasaki fans in the stands at Suwon World Cup Stadium, with a brawl breaking out as they blocked visitors trying to head for the exit.

The J. League first division side said traveling club officials confiscated the 16-ray rising sun flag from the two men while escorting other supporters out of the stadium.

The flag was the war flag of the Imperial Japanese Army until the end of World War II. Although it is still flown by the Japan Maritime Self-Defense Force, the flag is considered a symbol of Japan’s wartime aggression in many Asian countries, including South Korea.

The news comes just days after J. League chairman Mitsuru Murai apologized for the appearance of a Gamba Osaka supporter’s banner resembling a Nazi SS symbol at the April 16 derby match against Cerezo Osaka.