Tokyo has sent a message of protest to Beijing over an editorial by China's official news agency that demanded an apology from Emperor Akihito over Japan's wartime actions in the country, Chief Cabinet Secretary Yoshihide Suga said Friday.

The editorial, issued by the Xinhua news agency on Tuesday, is "very discourteous" to the Emperor and could adversely affect the Sino-Japanese relationship, which has been on its way to recovery in recent months, Suga told reporters in Tokyo.

"Yesterday, we strongly protested against China through a diplomatic channel," Suga said at a daily news briefing.

In the editorial, Xinhua claimed Emperor Hirohito, posthumously known as Emperor Showa, did not apologize to countries victimized by the war started by Japan and his son, Akihito, should apologize and repent to achieve reconciliation.

Suga claimed Xinhua's argument is "not consistent with China's (earlier) position" over the issue, without elaborating further, adding that the editorial is "not desirable at all."

According to the Yomiuri Shimbun, Chinese newspaper Guang Ming Daily carried the editorial on Wednesday's issue, but People's Daily, Beijng's official mouthpiece media, didn't reprint it.