Japanese history textbook that supports occupation has Korea livid.(Knight Ridder Newspapers)

SEOUL, South Korea _ An ugly spat over a proposed Japanese history textbook threatens to send relations between Japan and South Korea into a deep chill again, little more than a year before the kickoff of a World Cup soccer tournament that is supposed to highlight warmer ties.

On Thursday, thousands of protesters took to the streets of this capital to urge the Japanese government not to approve a junior high school text that maintains that Japan's colonization of South Korea, which ended in 1945, was legal and helped "stabilize East Asia" against the advances of the Anglo-Saxon world.

The dispute over how Japan views its past could easily unravel the good will that was generated after Japan and Korea agreed to co-host next year's World Cup soccer tournament. It also could reverse the diplomatic progress that has followed initiatives by South Korean President Kim Dae-jung to move beyond the historically strained ties between the countries, America's closest allies in the Western Pacific.

Carrying placards and Korean flags and waving their fists, protesters disrupted downtown traffic Thursday as they denounced their putative North Asian allies. "Japan is a developed country," said Lee Rae-won, 57, who was distributing flags in the street. "They should develop a sense of consciousness and some knowledge of their past. I worry about how they will educate their children."

The demonstration took place on the anniversary of the original 1919 protest against Japanese occupation of the Korean peninsula, a day celebrated as a national holiday here.

On Wednesday, Seoul's foreign affairs minister summoned the Japanese ambassador to express his concern over the proposed textbook, which was written by right-wing Japanese scholars hoping to cast Japan's imperialist war in East Asia in a favorable light.

And South Korea's National Assembly passed a resolution warning that it would stop its gradual opening of the domestic market to Japanese movies and music unless Tokyo rejects the offensive book.