China on Thursday said it was "deeply surprised and dissatisfied" with comments made by South Korean President Yoon Suk Yeol that appeared to accuse Chinese nationals of espionage.

Yoon made a defiant televised address earlier Thursday in which he defended his shock decision to declare martial law and send troops to the South Korean parliament last week.

The embattled leader also lashed out at China during his speech, accusing Chinese nationals of photographing and filming military sites in South Korea.

The Foreign Ministry hit back later Thursday, saying Yoon was "groundlessly hyping up so-called Chinese espionage".

"China... is deeply surprised and dissatisfied with these remarks made by the South Korean side," ministry spokeswoman Mao Ning said at a regular press briefing, without referring to Yoon by name.

"This is not conducive to the healthy and stable development of China-South Korea relations," she added.

During his address, Yoon accused the main opposition party of blocking his efforts to amend South Korea's anti-spying law.

He said current legislation left "no way to punish foreign nationals for espionage".

Mao said Thursday that Beijing "firmly opposes the South Korean side's linking internal issues with China-related factors".

She said the Chinese government always required Chinese citizens overseas to abide by local laws and regulations, and added that no conclusion had been reached regarding the case mentioned by the Republic of Korea. (Agencies)