Japanese media are reporting an explosion Monday in a public restroom at Tokyo's Yasukuni shrine, which honors Japan's war dead, including those executed as war criminals. No one was injured.

Yasukuni has been the target of criticism from Japan's neighbors, including China and South Korea, which suffered World War II atrocities and aggression.

Fire fighters received a call to put out a small fire Monday morning that damaged the ceiling and walls of the restroom, said an official at the Tokyo Fire Department who spoke on condition of anonymity. But the fire was out by the time they arrived. He declined to elaborate.

It was unclear what caused the explosion. TBS TV news said police suspect foul play, and batteries and wirings that may be part of an explosive device were found. Police will be reviewing footage on security cameras for clues on who might be behind the explosion, TBS said.

Tokyo metropolitan police declined comment as the case was still under investigation. The person in charge of media at Yasukuni was out and not immediately available for comment.

The shrine is a focal point for lingering tensions with Japan's neighbors over the country's aggression before and during World War II. Some Japanese lawmakers have insisted on making official visits in the name of patriotism, while other lawmakers say such visits glorify Japan's historical mistakes.

Emperor Akihito has not visited Yasukuni. Prime Minister Shinzo Abe has also avoided making official visits over the last two years.

While views on the shrine have also divided the Japanese public, it holds emotional significance for many because during the war soldiers promised each other they would reunite at Yasukuni if they died.

Many families and tourists visit Yasukuni, and Monday was a national holiday.

The shrine has a grandiose gate, giant cherry trees, flocks of pigeons and a museum that pays homage to those who died in Japan's wars, including kamikaze pilots.