Japan's government has disowned remarks by a mayor who claimed that sex slaves taken from invaded nations were a military necessity during the Second World War.

Osaka Mayor Toru Hashimoto prompted outrage by suggesting last month that battle-stressed soldiers needed the services of sex slaves, which were called "comfort women" by the Japanese.

On Saturday, the defence minister Itsunori Onodera told an Asian security conference that the administration of Prime Minister Shinzo Abe "never commits to such remarks or recognition of history".

The conference is being attended by nations attacked by Japan during that war.

"In the past, Japan caused tremendous damage and suffering to the people of many countries, particularly to those of Asian nations," Onodera told the security forum in Singapore known as the Shangri-La Dialogue.

"Consecutive Japanese governments have humbly acknowledged such historical facts, expressed deep remorse and genuine apologies," the minister added.

Up to 200,000 women from Korea, China, the Philippines were forced into sex slavery during the Second World War.

Hashimoto's comments provoked protests abroad, with South Koreans burning portraits of the mayor and the Japanese prime minister last month.

The Osaka mayor has cancelled a trip to the United States after US officials denounced his remarks as "outrageous and offensive".

He also retracted advice he gave to US military commanders in Japan that they should let their troops use licensed sex businesses as part of what he called a crime reduction strategy.

Source: Agencies