While requesting a meeting on the issue of compensating Japan's wartime forced labor last week, Tokyo is said to have pressed Seoul to respond in 30 days.
The details of the Japanese request were made known on Sunday.
Earlier on Wednesday, Tokyo asked Seoul for a meeting after a South Korean court seized Korea-based assets of Nippon Steel & Sumitomo Metal, a defendant in the forced labor case.
According to sources in Seoul on Sunday, the South Korean government plans to not to be tied down by the unusual 30-day deadline Japan insisted in violation of diplomatic courtesy.
South Korea said last week it will review the request carefully to decide on whether to accept it.
Japan's call for the talks is based on Article 3 of a 1965 treaty between Seoul and Tokyo that normalized bilateral ties. It stipulates that the two sides are to settle any dispute related to the treaty primarily through diplomatic channels. But the treaty doesn't specify any deadline for arranging diplomatic talks.