A group of US government officials and nuclear experts crossed the border Tuesday into North Korea to inspect its main nuclear facility and discuss the next phase of the denuclearization of the country, according to dpa. The seven-member delegation, led by Sung Kim, director of the Office of Korean Affairs at the US State Department, travelled from South Korea, crossing the land border and heading for Pyongyang, where he is to meet two nuclear experts from China and Russia, the South Korean news agency Yonhap reported. North Korea invited the experts for the inspections after it promised the United States last week to disclose all of its nuclear activities and dismantle its nuclear programme by the end of this year. Kim said that during their visit, the three nations' experts would survey the atomic facility at Yongbyon, about 90 kilometres north of Pyongyang. North Korea shut down the complex in mid-July in return for oil deliveries in the first step of its promised denuclearization. The shutdown was part of an agreement made between North and South Korea, the United States, China, Russia and Japan in February. Pyongyang, which had prompted fears that it was seeking to develop nuclear weapons, agreed to give up its nuclear programme in return for economic and energy aid and security and diplomatic guarantees that are to include normalizing its relations with Washington and Tokyo. The next round of six-nation talks are planned for later this month. Meanwhile, South Korean President Roh Moo Hyun said that reaching a permanent peace agreement for the entire Korean peninsula would top the agenda of talks scheduled for early October with North Korean President Kim Jong Il. Speaking to journalists in Seoul, he said: "Objectively speaking, the nuclear issue is in the midst of being resolved at the six-party talks," adding: "The declaration of the end of the Korean War and peace treaty are the core agenda times of the inter-Korean summit talks." Speaking after talks last Friday with Roh at the Asia-Pacific Economic Cooperation (APEC)in Sydney, US President George W Bush said the United States would consider a formal peace treaty with North Korea after Pyongyang gave up its nuclear weapons programme. Bush said Washington would formally end the 1950-53 Korean War only when North Korea gives up its quest for nuclear weapons. Peace was never declared in the Korean War. Hostilities were ended with a truce, not a peace treaty, and hostilities have thereafter governed the relationship between Washington and Pyongyang.