Pyongyang is also seeking to ramp up fissile material production, a UN report seen by the outlet says

North Korea laid the groundwork for a nuclear test in the first half of this year, Reuters reported on Friday, citing a confidential report submitted to a UN watchdog committee.

"Work at the Punggye-ri nuclear test site paves the way for additional nuclear tests for the development of nuclear weapons," independent monitors reportedly told the UN Security Council Sanctions Committee on North Korea.

According to Reuters, the experts also believe that North Korea "continued to develop its capability for the production of fissile material" at the Yongbyon site. The monitors were referring to the nuclear research center that was established with Soviet assistance in the 1960s and operates the nation's first nuclear reactors.

The monitors are also said to have accused the North of stealing crypto assets to the tune of hundreds of millions of dollars in an apparent effort to fund its missile and nuclear programs.

"Other cyber activity focusing on stealing information and more traditional means of obtaining information and materials of value to DPRK's prohibited programmes, including WMD (weapons of mass destruction), continued," the monitors reportedly added.

The report comes after CNN, citing unnamed US officials, revealed in early May that Pyongyang was getting ready for a nuclear test at the same location. The outlet's sources noted at the time that satellite images appeared to show personnel and vehicle activity at the testing ground. However, they said that it was unknown if North Korea had placed any fissile materials in one of the underground tunnels.

The US has vowed to push for steeper sanction against Pyongyang if it proceeds with its seventh nuclear test.

The UN Security Council has prohibited North Korea from carrying out nuclear tests and ballistic missile launches, imposing sanctions on the hermit state to stop it from funding the relevant programs. This, however, did not prevent Pyongyang from repeatedly test-firing missiles this year. One of the launches, which took place in March, apparently featured an intercontinental ballistic missile (ICBM).

In late July, North Korean leader Kim Jong-un announced that Pyongyang's "nuclear war deterrent" was "fully ready" to respond to threats. His warning came as the US and South Korea agreed to expand their joint military exercise that is scheduled for later this year.