WASHINGTON, May 4 (Reuters) - South Korea will soon engage with China at the senior level and also seek the opportunity for diplomacy aimed at trilateral cooperation with Japan and China, South Korea's ambassador to Washington Cho Hyun-dong said on Thursday (May 4).

Cho told an event hosted by Washington's Center for Strategic and International Studies that the COVID-19 pandemic had prevented high-level exchanges with China and there was a need for a new foundation of relations with its neighbour and number-one trading partner.

"Now we have a much-improved situation of the pandemic, then we're going to engage with China at the senior level and also, we are going to seek some opportunity of diplomacy in the context of trilateral cooperation between Seoul, Tokyo and Beijing," he said.

Cho said China probably had some "unhappy reaction" to Seoul's heavy diplomatic engagement with both the United States and Japan, particularly the Washington Declaration agreed at a summit between President Joe Biden and South Korean President Yoon Suk Yeol last week.

"But we'll definitely engage with China," he said. "We have to maintain a good relationship with China."

Economic leaders of Japan, South Korea and China said in a joint message after a meeting this week that they recognise the importance of strengthening economic and trade relations to secure post-pandemic growth and prepare for future shocks.

China expressed "strong dissatisfaction" to South Korea last week over Yoon's joint summit statement with Biden about the need for peace and stability in the Taiwan Strait.

At the Biden-Yoon summit, the United States pledged to give South Korea more insight into its nuclear planning over any conflict with North Korea amid anxiety over Pyongyang's growing arsenal of missiles and bombs.