NEW YORK, Aug. 21 (CGTN) -- The UN nuclear watchdog said it did not find any indication that the Democratic People's Republic of Korea (DPRK) had stopped its nuclear activities, adding to doubts about the country’s willingness to abandon its arsenal.

“The continuation and further development of the DPRK’s nuclear program and related statements by the DPRK are a cause for grave concern,” the International Atomic Energy Agency (IAEA) said in a report published late on Monday.

The report will be submitted to the IAEA’s board meeting next month.

The DPRK said it would immediately suspend nuclear and missile tests, scrap its nuclear test site and instead pursue economic growth and peace, ahead of a high-profile summit between DPRK leader Kim Jong Un and Republic of Korea's President Moon Jae-in in April.

In May, Pyongyang blew up tunnels at its main nuclear test site. A group of international journalists were invited to witness the demolition the Punggye-ri site.

During the landmark summit with US President Donald Trump in Singapore in June, Kim said his country is firmly and unwaveringly committed to the complete denuclearization of the Korean Peninsula.

On Monday, Trump told Reuters that he believed the DPRK had taken specific steps toward denuclearization and that he would “most likely” meet again with Kim.

The IAEA said verifying DPRK's nuclear weapons program would be a large and complex task.

“As the agency remains unable to carry out verification activities in the DPRK, its knowledge of the DPRK’s nuclear program is limited and, as further nuclear activities take place in the country, this knowledge is declining,” the IAEA said.