Satellite images show that North Korea has bored new tunnels near its Punggye-ri nuclear test site, indicating Pyongyang's intention to maintain its potential for future nuclear testing, a US website specialized in North Korean affairs said Thursday.

The images, taken on Dec. 28, 2017 and revealed Thursday by US-based website 38North, show that significant tunnel excavation activities were being carried out in the so-called Western Portal in Punggye-ri, in northeastern North Korea.

According to the images, mining carts and a group of about 100 or 120 workers were present in the area and there was an increase in spoil piles around the West Portal.

"These activities underscore North Korea's continued efforts to maintain the Punggye-ri site's potential for future nuclear testing," 38North concluded.

The US website also confirmed that the North Portal, where five of the six North Korean nuclear tests were carried out, including the latest and most powerful one last September, has remained in a dormant state.

The powerful nuclear test conducted on Sep. 3 is believed to have caused serious damage to the site and could make it collapse.

The satellite images were published shortly after the two Koreas held their first historic meeting in two years, which concluded with both countries' showing signs of reducing regional tension, after a year of Pyongyang's continuous weapons tests and US president Donald Trump's hostile remarks towards North Korea.

The meeting even led Trump to express his willingness to hold a dialogue with North Korea "at the appropriate time, under the right circumstances."

However, North Korean leader Kim Jong-un already said in his New Year message that, despite his desire to improve ties with South Korea, Pyongyang has no intention of suspending its nuclear program and will continue to develop its weapons to prevent Washington from attacking its territory.