The head of the U.S. Consulate in Fukuoka apologized Friday to the mayor of Sasebo for Monday's surprise call by a U.S. nuclear submarine at Sasebo port, city officials said.

Kevin Maher delivered his apology in Japanese to Akira Mitsutake and replied positively when asked by the mayor if he had come to the city hall to apologize, the officials said.

Maher said a U.S.-Japan joint panel will be launched Tuesday to discuss ways to ensure the U.S. Navy notifies Japan in advance of port calls by nuclear subs. Mitsutake, however, then reportedly asked that no sub calls be made for the time being, citing negative sentiment among locals.

The USS Chicago entered Sasebo port without prior notification Monday. The U.S. has been providing at least 24 hours notice of port calls by nuclear vessels to Japan since the first such visit in November 1964. The warnings are to facilitate preparations by local governments to measure radioactivity.

U.S. Secretary of State Colin Powell expressed regret over Monday's incident to Foreign Minister Yohei Kono on the phone Wednesday, adding that the U.S. will make efforts to enforce the notification arrangement more strictly.

Foreign Ministry officials said Wednesday the U.S. Navy had made a "simple error" that prevented it from notifying the Japanese government of where the Chicago planned to dock.

Since 1964, U.S. nuclear submarines have called at Sasebo, Yokosuka in Kanagawa Prefecture and Katsuren in Okinawa on more than 1,000 occasions. Monday was the first time prior notification was not given, according to the officials.