North Korea's premier, who is reportedly close to the son and heir apparent of leader Kim Jong-Il, has visited northeast China this week for talks with Chinese officials, state media reported.

Choe Yong-Rim -- who in late September was named a member of the ruling party's politburo presidium, of which Kim had been the only member -- met with Chinese Vice Premier Zhang Dejiang in Changchun, Xinhua news agency said.

It is the same region bordering the North that Kim toured for five days in late August -- a visit that state media said had largely focused on economic issues and analysts speculated included calls from Beijing to speed up reform.

Choe "congratulated China on its economic and social development" and said Pyongyang was "willing to draw experience from China and further strengthen its exchanges and cooperation with the country," Xinhua said late Wednesday.

Zhang said Beijing would work with the North to "promote the China-DPRK friendship to a new height", the report said.

South Korea's Yonhap news agency, citing unnamed sources, said Choe toured electronics and pharmaceutical companies in the region this week, as well as an agricultural research centre in the city of Harbin.

Xinhua did not specify when Choe and Zhang had met, nor did it say when Choe was due to return home.

Yonhap also reported that Choe was believed to be a key aide to Kim's son Jong-Un, in his late 20s, who in September was promoted to a four-star general and given powerful posts in the ruling party.

A senior Pyongyang official has officially confirmed he is the leader-in-waiting.

China -- North Korea's sole major diplomatic ally and is its economic lifeline -- has apparently given its blessing to another dynastic succession. President Hu Jintao has invited its new leadership to visit China.