The ongoing controversy between Japan and South Korea over a new textbook for Japanese junior high schools has taken a toll on the bilateral diplomatic calendar.

Diplomatic sources said Thursday that the row, as well as the increasing uncertainty over Japanese politics, have forced the two Asian neighbors to postpone a regular ministerial meeting originally planned for later this month.

Unpopular Prime Minister Yoshiro Mori is under growing pressure, not only from opposition parties but also from within his own ruling coalition, to step down ahead of Upper House elections this summer. Mori is widely expected to announce his resignation early next week.