Japan committed a "discourtesy" by canceling agreed-upon talks between President Moon Jae-in and Japanese Prime Minister Yoshihide Suga during the recent Group of Seven (G-7) summit in Britain, the head of South Korea's state diplomatic academy said Tuesday.

Kim Joon-hyung, chancellor of the Korea National Diplomatic Academy, also said on a local radio station that it is "diplomatically impolite" for Japan to press the South to accept its demands in a row over wartime forced labor as a precondition for a summit.

Seoul and Tokyo had tentatively agreed to hold a pull-aside meeting between their leaders during the three-day G-7 session that ended Sunday, a foreign ministry official said. But Tokyo unilaterally called it off, taking issue with Seoul's annual drills to defend its easternmost islets of Dokdo.

"That is, after all, Japan's discourtesy. But it's not a surprise," Kim said on the CBS radio station. "Though Japan denies it had canceled the meeting, it, in fact, had continuously put forward preconditions for a summit between the leaders to take place."

The preconditions included South Korea's adherence to the 1965 treaty aimed at normalizing bilateral relations after Japan's 1910-45 colonization of the Korean Peninsula and a 2015 deal to address the issue of Japan's wartime sexual slavery.

Japan argues that Seoul has failed to fully implement the treaty and the deal, as victims continue to call for Japan's reparations and full atonement through civil lawsuits.

Kim criticized preconditions for a summit as a "demand for a complete surrender."

"When the US said South Korea, the US and Japan should get together and get along well, and that Seoul and Tokyo should address their issues, Japan has always rejected it," he said.

Kim also said that Japan's preconditions for a summit appear to reflect its discomfort over South Korea having continued to stand out prominently at the G-7 gathering. (Yonhap)