The Japanese military's forced prostitution of Asian women before and during the Second Word War was necessary to "maintain discipline" in the ranks and provide rest for soldiers who risked their lives in battle, an outspoken politician has said.
Asian countries that bore the brunt of Japan's wartime aggression have long complained that Japan has failed to fully atone for wartime atrocities.
Speaking on Monday, Osaka Mayor Toru Hashimoto, who is also co-leader of an emerging conservative political party, also told reporters there was no clear evidence that the Japanese military coerced women to become what are euphemistically called "comfort women".
He said: "To maintain discipline in the military, it must have been necessary at that time. For soldiers who risked their lives in circumstances where bullets are flying around like rain and wind, if you want them to get some rest, a comfort women system was necessary. That's clear to anyone."
Historians say up to 200,000 women, mainly from the Korean Peninsula and China, were forced to provide sex for Japanese soldiers in military brothels.
An unidentified South Korean government official told Yonhap news agency it was disappointing that a senior Japanese official "made comments supportive of crimes against humanity and revealed a serious lack of a historical understanding and respect for women's rights".
Mr Hashimoto's comments come amid mounting criticism at the prospect of Prime Minister Shinzo Abe's conservative government revising Japan's past apologies for wartime atrocities.
Before he took office in December, Mr Abe had advocated revising a 1993 statement by then-Prime Minister Yohei Kono acknowledging and expressing remorse for the suffering caused to the sexual slaves of Japanese troops. Mr Abe has acknowledged "comfort women" existed but has denied they were coerced into prostitution, citing a lack of official evidence.
Over the past two days, top officials in Mr Abe's government have appeared to ease their concern over Japan's past apologies, apparently to calm tensions with South Korea and China and address US concerns about his nationalist agenda.
Chief cabinet secretary Yoshihide Suga told reporters that "the stance of the Japanese government on the comfort women issue is well known. They have suffered unspeakably painful experiences. The Abe Cabinet has the same sentiments as past Cabinets."