Foreign Minister Taro Kono on Sunday expressed concern about South Korean National Assembly Speaker Moon Hee Sang's recent remarks seeking an apology from Japan's Emperor Akihito to women forced to work in Japanese wartime military brothels.

"I want him to be careful about his remarks," Kono told reporters during a visit to Davao City in the Philippines. The minister said he believes a 2015 bilateral agreement solved the issue of so-called comfort women "finally and irreversibly."

"I understand that South Korea has not demanded renegotiation (of the 2015 accord), so I want (South Korean officials) to make remarks with a correct awareness," Kono said.

Many women from South Korea, as well as those from other countries, were forced to work in Japan's military brothels before and during World War II.

Bloomberg news service reported Friday that Moon called Emperor Akihito "the son of the main culprit of war crimes" during an interview conducted the previous day, referring to his father, Emperor Hirohito, Japan's monarch during World War II.

"If a person like that holds the hands of the elderly and says he's really sorry, then that one word will resolve matters once and for all," Moon said when asked how South Korea and Japan can end their long-running rows over wartime history.

"It only takes one word from the prime minister, who represents Japan -- I wish the emperor would do it since he will step down soon," Moon was quoted as saying. The 85-year-old emperor is set to abdicate on April 30, the first living Japanese monarch to do so in about 200 years.

Kono said the South Korean government has explained to him that the report did not reflect Moon's original intention.

Bilateral ties have long been strained over historical grievances related to Japan's colonial rule of the Korean Peninsula between 1910 and 1945.

The relationship has been under added pressure following a string of court rulings in South Korea in favor of wartime laborers seeking damages.

S. Korean assembly speaker says apology needed from Japan emperor