South Korea's presidential candidates faced off in a heated first TV debate on Sunday evening, ahead of a snap election on June 3 to choose a successor to former President Yoon Suk Yeol, who was impeached over his short-lived martial law declaration in December.

Lee Jae-myung, the main opposition Democratic Party's candidate and the front-runner in the race, has faced criticism from opponents as being too friendly to China, citing his comments that South Korea does not need to get involved in China-Taiwan disputes.

But Lee, who considers pragmatism as key to his foreign policy, said the country "should not go all-in" on its alliance with Washington, and said managing China and Russia relations was important, although security cooperation with the U.S. and Japan is necessary.