Pyongyang: China said it wants to strengthen ties with North Korea, its isolated neighbour under UN sanctions for its nuclear weapons programme, which is due to hold a massive military parade in the capital on Saturday to mark the 70th anniversary of its ruling Workers’ Party.

Foreign journalists have been invited to Pyongyang this week to cover the anniversary events, and on Saturday troop carriers could be seen lined up in the city, with the parade expected to take place later in the afternoon.

In a letter delivered by Liu Yunshan, the most senior Chinese official to visit Pyongyang since leader Kim Jong Un came to power following his father’s death in 2011, Chinese leader Xi Jinping said China attached vital importance to its relationship with North Korea, China’s official Xinhua news agency said late on Friday.

China is impoverished North Korea’s chief ally and its main trading partner, although ties have been strained over the North’s nuclear programme. North Korea is under UN sanctions for its nuclear tests and missile launches.

Xi said in the letter that China had ‘been striving to treat the bilateral relations from a strategic and long-term perspective’. Liu reiterated China’s position that it wanted an early resumption of the so-called six-party talks aimed at reining in North Korea’s nuclear ambitions.

‘The Chinese side is willing to seek closer communication and deepen cooperation, pushing for a long-term, healthy and stable development of the Sino-DPRK ties,’ Xi said in the letter cited by Xinhua, referring to North Korea by its official name, the Democratic People’s Republic of Korea.

Kim, who is in his early thirties, told the visiting Chinese delegation on Friday that North Korea was also keen to bolster ties, the North’s official KCNA news agency said on Saturday.

Liu is the fifth-ranked member on China’s ruling Communist Party’s elite Politburo Standing Committee.

On Wednesday, a high-level US military official said Washington believed North Korea had the capability to launch a nuclear weapon against the US mainland and stood ready to defend against any such attacks.

However, a planned launch of a satellite, which had been expected by officials in Seoul to be a centrepiece of Saturday’s celebrations, seems less likely to take place soon. Analysts and South Korean officials say there have been no visible signs of launch preparations.