State media issued pictures of Kim Jong Un inspecting centrifuges which are critical to developing weapons-grade uranium for nuclear bombs. North Korea has given a rare insight into the heart of its secretive nuclear weapons programme which produces fuel for atomic bombs. Images released by the country's state news agency (KCNA) showed - for the first time - the centrifuges at the centre of a uranium enrichment facility.

In a statement leader Kim Jong Un called for more weapons-grade material to increase the arsenal "to constantly confront with the US and contain it".

North Korea's nuclear weapons programme is banned under multiple UN Security Council resolutions.

State media reported on his visit to the Nuclear Weapons Institute - whose location was not disclosed - and accompanied their statement with photos of the centrifuges.

The machines are critical to enriching uranium so it can be used in nuclear bombs.

The North Korean leader said "anti-DPRK nuclear threats" from the "US imperialists-led vassal forces" have crossed the red-line, according to the report.Photos released by North Korea showed about 1,000 centrifuges which - when operated all year round - would be enough to create a single bomb, according to Yang Uk, a security expert at Seoul's Asan Institute for Policy Studies.On Friday, Russia's security council secretary, Sergei Shoigu, met Mr Kim in North Korea and discussed bilateral and international issues, Russia's Interfax news agency reported.

Mr Kim is deepening his military cooperation with Russia by supplying conventional arms to support Russia's war in Ukraine in return for military and economic aid.KCNA said in a separate report Mr Kim oversaw the test launch of a new 600mm rocket system, which a South Korean official said may have been to test the weapons for export to Russia.

Since 2022, North Korea has ramped up its weapons testing activities, and analysts believe the country could conduct a nuclear test explosion or long-range missile test ahead of the US presidential election in November.South Korea's Unification Ministry strongly condemned North Korea's "illegal" pursuit of nuclear weapons in defiance of UN prohibitions, adding it was a serious threat to international peace.

North Korea first revealed its uranium enrichment plant in Yongbyon in November 2010, and in recent years satellite images indicate the facility has been expanded.

In 2018, a top South Korean official estimated North Korea has already manufactured 20 - 60 nuclear weapons, but some experts think the total is more like 100.