South Korea's foreign minister was to hold bilateral meetings with his Chinese and Japanese counterparts in Seoul on Saturday on the sidelines of their trilateral talks, Seoul's foreign ministry said.

Foreign Minister Yun Byung-se was scheduled to meet with Chinese Foreign Minister Wang Yi and Japan's top diplomat Fumio Kishida in Seoul ahead of the three-way meeting, the ministry said.

Wang and Kishida flew into Seoul on Friday for a three-day stay to attend a trilateral foreign ministers' meeting that will be held for the first time in almost three years later in the day.

Kishida's visit marked his first trip to South Korea since he took up the post in December 2012.

The series of meetings comes as South Korea's and China's bilateral relations with Japan remain strained due to historical and territorial rows.

The talks also come at a time when Seoul's diplomacy has been put to test amid a mounting Washington-Beijing row over an advanced U.S. missile defense system on Korean soil and a China-led Asian development bank.

South Korea is struggling to walk a diplomatic tightrope between the U.S., Seoul's key ally, and China, Seoul's largest trading partner, over the sensitive security issue.

An official at Seoul's foreign ministry said that agendas for the Yun-Wang talks include the signing of a free trade agreement and other bilateral issues such as maritime border demarcation.

But experts said that China is widely expected to bring up the issue of Washington's possible deployment of a Terminal High-Altitude Area Defense (THAAD) battery on Korean soil.

Liu Jianchao, the Chinese assistant minister of foreign affairs, urged South Korea on Monday to take heed of Beijing's concern over the possible THAAD deployment in South Korea.

A day later, Seoul's defense ministry urged neighboring countries not to try to influence its decision on the THAAD deployment in what could be its thinly-veiled criticism of China's pressure against the move.

Also high on the agenda will be the issue of whether Seoul will join the China-led Asian Infrastructure Investment Bank (AIIB), experts said.

China launched the AIIB late last year with other 20 nations as a counterbalance to the Asian Development Bank, which is dominated by the U.S. and Japan.

South Korea plans to decide whether to join the AIIB soon while the U.S. has apparently pressed Seoul not to invest in the regional bank out of concerns over China's bid to increase its economic clout.

When it comes to Japan, Yun and Kishida are likely to discuss the issue of Japan's sexual enslavement of Korean women during World War II at the bilateral talks, officials said.

"They are expected to reaffirm the importance of improving Seoul-Tokyo ties as this year marks the 50th anniversary of the normalization of the relationship," the official said.

Since taking office in early 2013, South Korean President Park Geun-hye has shunned a bilateral summit with Japanese Prime Minister Shinzo Abe, calling on Japan to first sincerely apologize for the sex slavery issue.

The two sides have agreed to improve their stained ties during the landmark year, but no major progress in their regular talks on the sex slaves has been made due to Japan's refusal to face up to its wartime wrongdoings.

A Seoul official said Monday that the two sides "went beyond" the repetition of their respective stance at the latest talks.

But experts said there is a long way to go as speculation is growing that Abe will not include words of apology for Japan's past atrocities at his new statement due out in August to mark the 70th anniversary of the end of World War II. (Yonhap)