Koizumi said he didn't know why China suddenly canceled the meeting. "The other side asked for the meeting, and I thought it would be a good opportunity," he told reporters.
Government officials have speculated that behind the decision is friction between Japan and China over Koizumi's visit to the Yasukuni Shrine in Tokyo, the Mainichi Shimbun reported Monday.
Chinese President Hu Jintao had met Sunday in Beijing with senior legislators from Koizumi's Liberal Democratic Party and warned them that the visits to the Yasukuni shrine were endangering ties, China Daily said Monday.
At a news conference Monday morning, Chief Cabinet Secretary Hiroyuki Hosoda expressed regret over the cancellation. He said China had sent word that Wu must return to "handle sudden official duties."
Wu arrived in Japan last Tuesday to attend the China Day events Thursday as part of the Aichi Expo, and was to return home Tuesday.
During her visit she also met with business leaders in Nagoya and Tokyo, and called for talks toward a bilateral free-trade agreement.