The powerful uncle of North Korean leader Kim Jong Un met with both President Hu Jintao and Premier Wen Jiabao on Friday morning, after Beijing earlier in the week agreed to help Pyongyang revamp two trade zones near the Chinese border.

The high-level talks are a sign that Beijing and Pyongyang are strengthening ties after Kim took over following his father's death last year. State media have said the visit by Jang Song Thaek, the chief of the central administrative department of the Workers' Party of Korea, is a possible prelude to a visit by Kim himself. China remains North Korea's most important ally.

Jang is a vice chairman of the powerful National Defense Commission. He also is seen as a leading economic policy official.

The official China Radio International said the Friday morning meeting with Hu came toward the end of Jang's six-day visit and that Hu praised Jang for his "huge amount of work for the friendly relations between China and North Korea as two neighboring countries."

At a separate meeting, Wen told Jang that the China-North Korea friendship has endured historical tests and is a shared treasure. He said Jang's visit will deepen the relations between the two ruling parties and the two nations, according to the official China News Service.

Hu and Wen expressed their condolences to the recent flood victims in North Korea, state media reported.

Jang met Chinese commerce ministry official earlier this week to discuss the development of the special economic zones in North Korea.

The ministry said the two sides signed a number of cooperation agreements to further develop two special economic zones -- Rason on the Korean Peninsula's northern tip, and Hwanggumphyong, an island in the Yalu River that marks their border to the southwest.

Rason would be developed into a manufacturing base, logistics center and tourism hub and that the Hwanggumphyong zone would focus on information technology, tourism, agriculture and garment manufacturing, it said.

Jang met with Wang Jiarui, the head of the international department of the Communist Party of China Central Committee, on Thursday.