Diplomacy often takes place on the sidelines of international gatherings -- an impromptu tete-a-tete between global leaders at a coffee break, or a chance encounter in the corridors of a convention centre.

It took a new form at a meeting of Asian officials on Wednesday when the Japanese and Chinese foreign ministers ran into each other in the men's room.

"I had meaningful discussions with Minister Li at the toilet," a Japanese official quoted Foreign Minister Taro Aso as telling the meeting of Asian ministers, referring to his Chinese counterpart, Li Zhaoxing.

While Aso and Li are due to see each other -- at a hotel room -- on Thursday, their meetings have been hardly frequent, reflecting the icy ties between the Asian neighbours.

Their last meeting in May, also on the sidelines of a regional forum in Qatar, was the first in about a year.

Asked whether Aso went to the men's room knowing Li was there, the Japanese official said it was purely nature's call.

"It was awfully cold in the conference room."

Relations between Tokyo and Beijing have deteriorated since Japanese Prime Minister Junichiro Koizumi came to power in 2001 and began annual visits to a Tokyo shrine for the war dead that China sees as a symbol of Japan's past militarism as it also honours some convicted war criminals.