Prime Minister Yoshihiko Noda is sending a personal letter to Chinese President Hu Jintao to express Japan's wish to defuse the tensions stemming from the Senkaku Islands dispute, government officials said Tuesday.

Senior Vice Foreign Minister Tsuyoshi Yamaguchi was scheduled to arrive in China later in the day to deliver Noda's personal message calling for deepening ties on the occasion of the 40th anniversary this year of the normalization of diplomatic relations between the two countries, the officials said.

After an assault Monday in Beijing on a vehicle carrying Japanese Ambassador Uichiro Niwa, Chief Cabinet Secretary Osamu Fujimura called the incident "very regrettable" and said Tokyo has asked Beijing to prevent similar incidents and investigate it as a criminal case.