BEIJING (REUTERS, AFP) - A senior Chinese diplomat will visit North Korea from Friday (Nov 17) as a special envoy of Chinese President Xi Jinping, the government announced on Wednesday, amid continued tensions over Pyongyang's nuclear and missile programmes.

China has repeatedly pushed for a diplomatic solution to the crisis, but in recent months has had only limited high-level exchanges with North Korea. February last year was the last time China's special envoy for North Korea visited the country.

In a brief dispatch, the official Xinhua news agency said Song Tao, who heads the ruling Communist Party's external affairs department, would leave for North Korea on Friday.

He will "inform the DPRK of the 19th CPC National Congress and visit the DPRK", Xinhua said, using the North's official name and also referring to the recently concluded Communist Party Congress in China where Xi further cemented his power.

North Korea's KCNA news agency confirmed the visit, but said only that it would take place "soon".

It is not clear how long Song could stay, but he has already visited Vietnam and Laos to inform them of the results of the congress, a typical courtesy China extends other communist countries after such important meetings.

Song's department is in charge of the party's relations with foreign political parties, and has traditionally served as a conduit for Chinese diplomacy with North Korea.

A department official said last month that China's Communist Party continues to hold talks and maintain contacts with its North Korean counterpart, describing the two countries friendship as important for regional stability.

China's new special envoy for North Korea, Kong Xuanyou, who took up his position in August, is not believed to have yet visited the country since he assumed the job.

Washington has urged China to intensify use of its economic leverage over North Korea to strongarm Pyongyang into halting its nuclear weapons and missile programmes.

US officials want Chinese authorities to clamp down on unauthorised trade that they say is still trickling across the North Korean border.

"China can fix this problem easily and quickly, and I am calling on China and your great president to hopefully work on it very hard," Trump said alongside Xi last Thursday. For his part, Xi repeated his plea for the issue to be resolved through negotiations, saying China was ready to discuss the "pathway leading to enduring peace and stability on the peninsula".

Xi has never met North Korean leader Kim Jong Un. The last Chinese official trip there was in October 2016, when vice foreign minister Liu Zhenmin visited.

On Sunday, Trump said Xi stated that "he is upping the sanctions against" North Korea, but he did not provide details and China has not announced any new punitive measures.

Beijing fears pressuring Kim's regime into collapse, triggering a flood of refugees across its border and eliminating a strategic buffer separating China from the US military in South Korea.