The mayor of Osaka, Japan and leader of the Japanese Restoration Party said this week that he believes the use of sex slaves during World War II, then known as "comfort women," was "something necessary" to keep up soldiers' morale.

Toru Hashimoto made the comments during a press conference Monday, according to NBC News.

“Whether it was of their own volition or against their will, the comfort women system was something necessary,” he reportedly said. “For military morale back then, it was probably necessary.”

"When a group of men is risking their lives, when this group of men are in a psychologically tense state, ... anyone could understand that they would need something like the comfort women system," Hashimoto added.

He also said that U.S. soldiers stationed in the country should spend more time frequenting sex workers, according to The New York Times, suggesting that may lower incidences of sexual violence.

Former Japanese Prime Minister Tomiichi Murayama personally apologized in 1994 for the nation's policy of forcing women into prostitution during World War II, although his words were met with disdain by numerous survivors, most of them South Korean women who were kidnapped and forced to serve Japanese soldiers.

“This is not something that’s coming out of our party, I think Mr. Hashimoto was expressing his own private opinions,” a top Japan Restoration Party official told NBC. “If these comments continue, we will need to look into his true intentions and put a stop to this.”