Seoul should "weigh the pros and cons with a cool mind" over its plan to introduce the THAAD anti-missile system from the US, and China and the Republic of Korea should jointly find solutions acceptable to both sides, Foreign Minister Wang Yi said on Wednesday.

He made the comments when he met with his ROK counterpart Yun Byung-se in Tokyo on the sidelines of the annual China-Japan-ROK foreign ministers' meeting.

China has voiced strong protests in recent months to the decision by the ROK to deploy the Terminal High Altitude Area Defense system, partly because its X-band radar is capable of covering parts of China.

Wang reiterated on Wednesday China's objections and said "currently the China-ROK relationship is faced with difficulties and challenges".

Wang noted that Wednesday marked the 24th anniversary of the establishment of China-ROK diplomatic relations and the two countries, he said, have seen hard-won achievements and neither side can allow these to be disrupted or sabotaged.

As the ROK is also a member of the G20, Wang said China welcomes the ROK President Park Geun-hye's trip to China to attend the G20 summit in Hangzhou in September, and Beijing is willing to maintain communication channels with Seoul.

Yun said the foreign ministers' meeting, held ahead of the G20 summit, shows the ROK fully supports China efforts to ensure a successful hosting of the event.

Next year marks the 25th anniversary of the establishment of diplomatic ties, and the ROK hopes to take this as a chance to boost mutual trust, Yun said.

Seoul is ready to boost cooperation with Beijing in regards to hosting the two respective Winter Olympic Games in both countries and deepen the friendship between the two nations, he added.

Cai Hong in Tokyo contributed to this story.