TOKYO — Fire destroyed the home and office of a Japanese lawmaker who has been critical of Prime Minister Koizumi’s visit to a reviled war shrine, police said yesterday. Protesters again demonstrated against Mr. Koizumi’s pilgrimage, which further eroded Japan’s ties with its neighbors just a month before he leaves office.

The fire broke out yesterday afternoon at the home and office of Koichi Kato in Yamagata prefecture, in northern Japan, destroying the buildings, according to a local police official, Koji Suzuki.

An unidentified man was found collapsed on the premises with wounds to his abdomen and was rushed to a hospital, Mr. Suzuki said. No other injuries were reported.

Police suspect arson, Kyodo News agency and TV Asahi reported. Mr. Suzuki said police were investigating how the fire broke out and that arson “could not be ruled out.”

It was not immediately clear whether the wounded man was suspected of setting the fire. Mr. Kato was in Tokyo when the fire broke out, but immediately returned home, according to news reports.

A veteran lawmaker of the ruling Liberal Democratic Party, Mr. Kato is known for his criticism of Mr. Koizumi’s visits to Yasukuni Shrine, which honors convicted war criminals among Japan’s war dead.

Mr. Koizumi worshipped at the shrine early yesterday, the anniversary of Japan’s World War II defeat, drawing praise from some war veterans and rightists who believe Japanese leaders should have the right to honor the war dead as they please.

But the early-morning pilgrimage prompted protests in China and South Korea, which suffered heavily under Japanese occupation. The countries view the shrine, which honors war criminals among Japan’s 2.5 million war dead, as a glorification of imperialism.

Mr. Kato had made numerous TV appearances yesterday saying Mr. Koizumi should not have visited the shrine just to satisfy his own beliefs. Mr. Koizumi says he goes to Yasukuni to pray for peace and honor fallen soldiers.

The impact of the visit to Yasukuni Shrine, Mr. Koizumi’s sixth as prime minister, was heightened by its timing on August 15, a date viewed with sadness in Japan as the anniversary of its World War II surrender but celebrated as a day of liberation from Japanese colonial rule elsewhere in Asia.

President Roh of South Korea called on Japan to “prove it has no intention to repeat”its past aggression as his government summoned the Japanese ambassador to issue an official protest.

In Beijing, flag-waving protesters gathered outside the Japanese Embassy, as Foreign Minister Li Zhaoxing of China condemned Mr. Koizumi for “obstinately” visiting the shrine. He also summoned Japan’s ambassador to issue a protest.

Mr. Koizumi defended the Yasukuni visit — his first as prime minister on August 15 — by saying that he goes there to pray for peace and to honor fallen soldiers, not to glorify militarism.

He also accused China and South Korea of using the issue to pressure Japan. Both countries have refused to hold summits with Mr. Koizumi unless he stops the pilgrimages.

“I have told them that my visits to the shrine should not be used as a diplomatic card,” Mr. Koizumi said. “I have expressed my view that making the decision over whether or not to hold summit meetings based on whether I visit the shrine is not a good thing.”

The shrine visits have been a lightning rod for critics who accuse Japan of failing to fully atone for its military invasions of its neighbors in the 1930s and 1940s. The shrine played a leading role in whipping up war fever in the first half of the 20th century.

Yesterday’s visit came a little more than a month before Mr. Koizumi is scheduled to step down as prime minister, leaving his successor with Tokyo’s relations with its neighbors at their most strained in decades.

“China and South Korea naturally issued strong protests, and they could even recall ambassadors,” a specialist on Southeast Asia at Tokyo’s Sophia University, Yoshinori Murai, said. “I think this will leave serious problems behind.”

Japanese public opinion is split over the visits. While many feel Japanese leaders should have the right to honor the war dead, others fear alienating Japan’s neighbors. A slew of lawsuits argue that the visits violate the division between the state and religion.

Both the leader of Mr. Koizumi’s junior coalition partner, the New Komei Party, Takenori Kanzaki, and Finance Minister Sadakazu Tanigaki criticized the pilgrimage. Other critics were the opposition Democratic Party of Japan, a Buddhist organization, and a group of relatives of war dead.

Supporters, however, said the visits are justified. War veterans and ultra-rightists thronged the shrine yesterday, some carrying banners with slogans that read: “The Greater East Asia War was not a war of aggression.”

The shrine is also working to win more support from the young, many of whom are tired of bearing the war guilt of their elders. Yu Ushiyama, 19, said foreign critics were just using the visits to browbeat Japan.

“We owe our lives to those who are honored here,” he said at the shrine yesterday. “Even without the Yasukuni issue, China and South Korea would criticize Japan because of other issues.”