TOKYO, Feb. 18 -- The U.S. ambassador to Japan avoided an interview with public broadcaster NHK partly due to its president's controversial remarks on wartime sex slavery, Kyodo News reported on Monday.

The U.S. embassy noted its disapproval of the remarks on "comfort women" made by Katsuto Momii, the head of NHK, as a reason for denying the interview request, Kyodo News reported citing "sources close to the decision."

The embassy also expressed its concern about controversial statements made by best-selling author Naoki Hyakuta, also an NHK board member who has described the U.S. air raids on Tokyo during World War II as "genocide" and has denied Japan's responsibility for the 1937 Nanjing Massacre.

NHK's effort to interview U.S. ambassador Caroline Kennedy has not paid off because comments made by Momii and Hyakuta triggered "concerns by the ambassador and Washington that an appearance on NHK would negatively impact the country's image," according to the sources.

Momii made the controversial remarks on Jan. 25 during his first press conference as NHK president, when he told reporters that "comfort women," the euphemistic term for women forcibly recruited to provide sex to Japanese soldiers during World War II, were used in "every country" and that the practice should not be judged by "today's morality."

He then went on to say that the issue was "complicated because South Korea says Japan was the only country that forcibly recruited" women.

Momii later apologized for the remarks, saying they represented his personal opinion.

Momii's remarks were strongly condemned by China and South Korea, who suffered the most during Japan's wartime atrocities.

"His words show that a force in Japan attempting to downplay or even deny Japan's war crimes," Chinese Foreign Ministry spokesman Qin Gang told a daily press briefing on Jan. 27.

Qin said that sexual slavery was a heinous crime committed by the Japanese military during the Second World War, which still harms victims' physical and mental health to this day.

"It is deplorable that the head of Japan's public broadcaster, who should remain fair and impartial, has distorted historical facts and made such a ridiculous claim," a South Korean foreign ministry spokesman said on Jan. 29.

"The thoughtless remark by the NHK chairman clearly illustrates that historical awareness among leading Japanese figures in Abe's Japan has diminished to a dangerous level," the spokesman said.