Three representatives of wartime "comfort women" who were forced into sexual servitude during World War II authorized a lawyer to hand over a protest letter at the Japanese embassy in Beijing and mail a copy to the Osaka government on Monday.

The protest came after Osaka Mayor Toru Hashimoto's remarks on May 13 that the practice was "necessary to maintain discipline" in the Japanese military during the war.

"They wanted to lodge a protest in May, but they are old and sick. Two are bedridden and the other has failing eyesight," Kang Jian, the lawyer, who works with the Fangyuan Law Firm in Beijing, told China Daily on Monday.

"I was 14 when forced by the Japanese army to sustain the brutal torture, which left us in agony and humiliation for a lifetime and only a small number of us survived," Guo Xicui wrote in the letter.