SEOUL - South Korean President Park Geun-Hye on Wednesday urged Chinese leader Xi Jinping to make "further efforts" to dissuade North Korea from conducting a fresh nuclear test, warning of serious repercussions for regional stability.
Her comments, made during a phone call between the two presidents and reported by her office, came a day after South Korea said heightened activity at the North's main nuclear test site might indicate an imminent test.
According to the presidential Blue House, Park voiced appreciation for China's attempts to get the North to suspend its testing programme.
"She asked for further efforts to persuade North Korea, saying additional nuclear tests would completely alter the region's security map by triggering an arms race and a nuclear domino effect in the region," it said.
As North Korea's only major ally, China has long shielded it from the severe sanctions the US and allies would like to impose, but it has also voiced exasperation at Pyongyang's provocative, bellicose behaviour.
According to the Blue House, Xi said it was in everyone's interest to avoid a rise in military tensions on the Korean peninsula.
North Korea has conducted three nuclear tests - in 2006, 2009 and 2013 - all at the Punggye-ri site in the northeast of the country.
South Korea's defence ministry said Tuesday that stepped-up activity at Punggye-ri indicated a fourth test might be in the pipeline.
However, spokesman Kim Min-Seok also acknowledged it could be a "deception tactic" to raise tensions before US President Barack Obama's arrival in Seoul on Friday.
The United States said Tuesday it was watching North Korea "very closely" following the warnings from Seoul.
The US-Korea Institute at Johns Hopkins School of Advanced International Studies said recent satellite images did indeed show "new operations" at Punggye-ri.
But it added that a test to coincide with Obama's visit was unlikely since the activity did not appear to have reached the same level of intensity as before previous tests.