Japan's top government spokesman said Tuesday it will be too early to comment on the prospect of South Korea joining the 11-member Trans-Pacific Partnership before it becomes clear whether the country can fully meet the high standards of the free trade pact.

South Korea expressed its willingness to join the pact the previous day. The U.K., China and Taiwan have already applied for membership of the pact, which does not include the United States following its abrupt withdrawal from negotiations in 2017.

"What we need to do first is to see if an economy that seeks to join the pact is fully prepared to reach the high levels of the TPP 11," Chief Cabinet Secretary Hirokazu Matsuno told a news conference.

"We will continue to follow developments related to economies with an interest in joining the pact, and respond by taking into account our strategic standpoint and public understanding," he said.

The pact, formally known as the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP), entered into force in 2018, cutting tariffs and setting high-standard rules for e-commerce, intellectual property and state-owned enterprises.

South Korean finance minister Hong Nam-ki said Monday that Seoul will begin the process of joining the CPTPP. Approval from the current 11 members is necessary to join.

Japan's relations with South Korea remain chilly over issues stemming from wartime history, with the two countries embroiled in a dispute over compensation for wartime labor.

Japan has welcomed the envisaged accession to the CPTPP by the U.K. and Taiwan, but has taken a cautious stance on China.

Farm minister Genjiro Kaneko refrained from commenting on how the Japanese government views South Korea's potential accession, telling reporters that no formal application had been filed.

The CPTPP's 11 members are Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore and Vietnam.