Japan has warned South Korea that it will take "countermeasures" if Seoul moves ahead with selling seized assets of a Japanese company that has refused to pay compensation in line with a ruling over wartime forced labor, diplomatic sources said Thursday.

Options apparently under discussion within Japan's government include raising tariffs on South Korean imports and recalling Japan's ambassador to Seoul, which would worsen bilateral ties already marred by disputes over the wartime labor issue and recent military incidents.

The Japanese government is expected to finalize its countermeasures soon. A 30-day deadline was set Friday for Seoul to respond on whether it will accept Tokyo's request to launch bilateral consultations aimed at resolving the issue of the asset seizure. No response had been reported as of Friday evening.