China abruptly canceled a meeting Monday between China's vice premier and Japanese Prime Minister Junichiro Koizumi (search), cutting short a visit aimed at repairing severely strained relations.

China's Foreign Ministry said Vice Premier Wu Yi had to return to Beijing for urgent but unspecified matters at home. Japanese officials said they had no further details and expected a full explanation.

The Japanese leader seemed surprised by the sudden change in plans.

"It was their (China's) request to hold a meeting, and I thought it would have been a good opportunity," Koizumi told reporters. "I don't understand why they're canceling it now."

Violent anti-Japan protests broke out in China in April amid tensions over a territorial dispute, clashes over maritime natural resources and differences over interpretations of World War II history. Beijing has been angered by Koizumi's annual pilgrimages to a Tokyo war shrine, saying they ignore Chinese sensitivities and pay homage to Japan's militarist past.

After Wu's departure, the Chinese Foreign Ministry released a statement saying she had to "return home to handle important and urgent official business." It did not elaborate.

A Japanese Foreign Ministry official said on condition of anonymity that senior diplomats expected Beijing to show them the "courtesy" of a full explanation, but Japanese media said Tokyo wouldn't formally request one.

Shinzo Abe (search), a top official of Koizumi's ruling Liberal Democratic Party, said he didn't think the cancellation would be seen as a major snub because Wu is not Koizumi's counterpart.

"But I'm afraid many Japanese may find it rather impolite," he said.

Japanese officials insisted they didn't think the cancellation was due to something Tokyo had done.

Chief Cabinet Secretary Hiroyuki said it was unlikely the pullout was connected to Koizumi's recent justifications for his visit to a Tokyo war shrine — visits which have been fiercely criticized by China.

Koizumi also rejected the idea that the cancellation was Tokyo's fault.

"I have tried not to have a negative influence (on Japan-China relations)," he said. "We'll meet whenever they want to."

Wu had originally been scheduled to leave Tuesday.

In her speech before a group of leaders of Japan's key business lobby Keidanren later Monday, Wu did not mention the cancellation of her talks with Koizumi, and only said she hoped the two countries work together to improve their ties.

"Today, China and Japan face serious challenges in their relations but also opportunity to improve and develop them," Wu said. "I sincerely hope the governments and the people of China and Japan will make efforts to address the problems and take steps."

Japan's Foreign Ministry said it was also committed to "deepening the dialogue" with China and promoting a "future-oriented" relationship.