SEOUL: U.S. House of Representatives Speaker Nancy Pelosi and her South Korean counterpart vowed on Thursday to support efforts to maintain a strong deterrence against North Korea and achieve its denuclearisation.

A joint statement was issued after Pelosi met South Korea's National Assembly Speaker Kim Jin-pyo in Seoul, in which they expressed concerns over the North's evolving nuclear and missile threats.

"Both sides expressed concerns about the dire situation of North Korea's growing threat," the statement said.

"We agreed to support the efforts of the two governments to achieve practical denuclearisation and peace through international cooperation and diplomatic dialogue, based on the strong and extended deterrence against the North."

Pelosi also said at a news conference that she and Kim discussed ways to boost cooperation on regional security and economic and climate issues.

Pelosi arrived in South Korea late on Wednesday following a brief stop in Taiwan, and met U.S. embassy officials in Seoul earlier on Thursday before talks with Kim and other lawmakers.

Later on Thursday, Pelosi plans to visit the Joint Security Area near the heavily fortified inter-Korean border, patrolled together by American-led U.N. Command and North Korea, a South Korean official said.

She would be the highest-level U.S. official to visit the area after former President Donald Trump, who met North Korean leader Kim Jong Un there in 2019.

South Korean President Yoon Suk-yeol, who was on a scheduled vacation this week, will not meet Pelosi but would speak to her by telephone later on Thursday, Yoon's office said.

South Korean media speculated that Yoon could be shunning meeting Pelosi in order to avoid antagonising China, after her visit to Taiwan caused outrage in Beijing, which claims the self-governed island as its own. 

An official at Yoon's office said it welcomes Pelosi and wishes her smooth travel, but did not comment on those reports.

"Our position on her visit to Taiwan is that we will continue close communications with other countries based on the view that maintaining regional peace and stability via dialogue and cooperation is important," the official told reporters.