North Korea has been excavating a new tunnel at its nuclear test site in the country's northeastern tip, an official said on Friday, in what may be a show of its nuclear capability, according to Yonhap News Agency.

The North has so far conducted three nuclear tests in tunnels at Punggye-ri, in 2006, 2009 and 2013.

"An increased movement of people and cars has been spotted at the nuclear site," said the official, asking not to be named. "North Korea appears to be in the process of digging another tunnel."

Another source said that the North's move indicates its intention to conduct a fourth nuclear test although more analysis is needed to access whether the test is imminent.

The detection came more than a month after the North hinted that it may conduct a nuclear test in response to what it claims is the hostile policy of the United States and its allies.

It also came ahead of a planned trilateral summit among South Korea, China and Japan slated for Sunday.

Experts said that North Korea seems to want to demonstrate its nuclear capability ahead of a series of summits involving the three nations.

Source: MENA