TOKYO, July 19 (Reuters) - Japanese Prime Minister Yoshihide Suga and South Korean President Moon Jae-in will hold their first in-person summit on Friday, coinciding with the start of the Tokyo Olympics, Japan"s Yomiuri newspaper reported on Monday. The report of Moon"s visit comes amid a political uproar in Seoul triggered by comments by a Japanese diplomat on Moon that created new tension in already fraught diplomatic relations between the two countries. Moon"s office said on Monday the visit was still uncertain. The leaders are likely to discuss issues that have strained relations over generations, including compensation for people forced to work in Japanese firms and military brothels during Japan"s 1910-1945 colonial rule, the Yomiuri report said. Japan is also planning to replace a senior Seoul-based diplomat after his widely reported comment last week likening Moon"s dealings with Japan to "masturbation", the Yomiuri said. On Monday, the South Korean presidential Blue House said in a statement that the two countries were in discussions but that there has been no decision on a trip by Moon. "It is still uncertain whether a visit to Japan and a meeting will take place as there has been no satisfactory action taken by the Japanese side over the last-minute obstacle to a (summit) meeting," it said. South Korean broadcaster JTBC reported on Friday that a senior diplomat at Japan"s embassy in Seoul had said Moon was "masturbating" when describing the South Korean leader"s efforts to improve ties with Tokyo. South Korea’s vice foreign minister, Choi Jong-kun, summoned Japan"s Ambassador Koichi Aiboshi on Saturday to protest. "He also demanded the Japanese government to promptly take tangible and due steps to prevent a recurrence of such situation," the foreign ministry said in a statement. A Japanese foreign ministry spokesman said no one could immediately comment on the reports. Suga this month called relations between Japan and South Korea "very difficult", adding that it was up to Seoul to provide a response to the problems. South Korea"s presidential Blue House has said a visit by Moon may be possible if he could meet Suga and if progress on some agreements could be expected.