Seoul, Feb 25 (IANS): Recent satellite images released by a monitoring group showed continued activity at the North Korean nuclear test centre of Punggye-ri, although no imminent test was expected.

The photographs, taken by 38 North on February 18 and released on Friday, show maintenance and refurbishment operations at the complex's galleries, especially in the North Portal, the site of the last year's underground detonations, Efe news reported.

In this area, "the location of equipment or supplies... has shifted repeatedly since October 2016," according to 38 North, a website that specialises in analysis of North Korea and is linked to Johns Hopkins University, US.

"The shifting of supplies and equipment as well as additional changes in the texture and pattern of small sections of the tailings pile at the North Portal indicate continuing work inside the test tunnels," the group said.

According to 38 North, these activities suggest that the portal is being maintained and prepared for use in a new nuclear test.

"Should the decision be made to do so, North Korea could probably move forward with a nuclear test in short order but it remains unclear when such a test might take place," it said.

In 2016, the regime of Kim Jong-un carried out two nuclear tests at Punggye-ri in a period of eight months.

The tests and the launch of a space rocket - widely suspected to be a covert intercontinental ballistic missile test - led to the approval of two new sanctions packages by the UN Security Council.