South Korean President Park Geun-hye asked Chinese President Xi Jinping to help persuade North Korea not to carry out a nuclear test, her office said Wednesday, a day after Seoul reported increased activity at the North's nuclear test site.

Park made the request when she spoke by phone with Xi on Wednesday morning, saying an additional nuclear test by the North would fundamentally change the security landscape in Northeast Asia as it would spark an arms race and a "nuclear domino" effect in the region, according to her office.

The communist North previously carried out nuclear tests in 2006, 2009 and 2013.

Xi told Park that it is in the interest of both countries to prevent an escalation of tensions on the Korean Peninsula, adding that China is doing its best to help maintain peace and stability on the peninsula, including encouraging dialogue between the related countries, Park's office Cheong Wa Dae said.

Xi also told Park that China and South Korea have the same position on opposing a nuclear North Korea, it said.

On Tuesday, Seoul's defense ministry said there has been a lot of activity at North Korea's Punggye-ri nuclear test site in the country's northeast, though such activity could also be a bluff designed to draw international attention ahead of a visit to South Korea by U.S. President Barack Obama.

The ministry has formed a task force to cope with a possible nuclear test. (Yonhap)