Toru Hashimoto said former comfort women should be offered "kind words"
A prominent Japanese politician has described as "necessary" the system by which women were forced to become prostitutes for World War II troops.
Osaka Mayor Toru Hashimoto said the "comfort women" gave soldiers putting their lives at risk a chance "to rest".
He acknowledged that the women had been acting "against their will".
Some 200,000 women in territories occupied by Japan during WWII are estimated to have been forced into becoming sex slaves for troops.
Many of the women came from China and South Korea, but also from the Philippines, Indonesia and Taiwan.
Japan's treatment of its wartime role has been a frequent source of tension with its neighbours.
Mr Hashimoto, the co-founder of the nationalist Japanese Restoration Party, was the youngest governor in Japanese history before becoming mayor of Osaka.
He said last year that Japan needed "a dictatorship".
In his latest controversial comments, quoted by Japanese media, he said: "In the circumstances in which bullets are flying like rain and wind, the soldiers are running around at the risk of losing their lives,"
"If you want them to have a rest in such a situation, a comfort women system is necessary. Anyone can understand that."
He also claimed that Japan was not the only country to use the system, though it was responsible for its actions.
He said he backed a 1995 statement by Japan's then-PM Tomiichi Murayama, in which he apologised for its wartime actions in Asia.
"It is a result of the tragedy of the war that they became comfort women against their will. The responsibility for the war also lies with Japan. We have to politely offer kind words to [former] comfort women."