Despite periods of strained ties between China and North Korea over Pyongyang's nuclear programme, the neighbours have maintained a close relationship in recent years.

Premier Li Qiang "will lead a party and government delegation to the DPRK... and pay an official goodwill visit from October 9 to 11", a foreign ministry spokesperson said in a statement, using an official acronym for North Korea.

Li, China's highest-ranking leader after President Xi Jinping, will attend 80th anniversary celebrations for North Korea's ruling Workers' Party, the statement said.

South Korea's Yonhap news agency reported last week that the North appears to be preparing for a large-scale military parade to mark the party's anniversary.

During a meeting in Beijing late last month, China's top diplomat Wang Yi called on his North Korean counterpart to strengthen the partnership.

Just weeks before, North Korean leader Kim Jong Un paid a rare visit to the capital city, where he stood alongside Xi at a parade commemorating the 80th anniversary of the end of World War II.

China is a vital source of diplomatic, economic and political support for North Korea.

Pyongyang justifies its nuclear weapons by citing threats it claims to face from Washington and its allies, including South Korea.