A powerful North Korean official and uncle of leader Kim Jong-Un has returned home, state media said, after high-level talks in Beijing which are seen as a precursor to a visit by Pyongyang's young ruler.

Jang Song-Thaek arrived from Beijing Saturday, the official KCNA news agency said, a day after he met China's President Hu Jintao on a trip focused on beefing up economic ties.

The six-day trip by Jang, head of the Central Committee of the North's ruling communist party, was the highest-level diplomatic exchange since the young leader took over from his late father Kim Jong-Il in December.

China is the sole major ally and economic lifeline for the impoverished but nuclear-armed North.

Beijing has provided food and fuel aid to the North, which is beset by chronic shortages, a moribund economy and international sanctions, and has urged Pyongyang to launch economic reforms.

The two nations signed agreements aimed at pushing forward the development of special North Korean economic zones near the Chinese border, the commerce ministry in Beijing said earlier.

China's Hu, during the talks with Jang, vowed to boost ties between the neighbours.

"We hope that both sides will... (push) forward the cooperation and development of the two economic zones and other major projects," a Chinese foreign ministry statement quoted Hu as saying during the talks Friday.

Jang also held talks with Chinese Premier Wen Jiabao, who addressed the importance of strengthening economic relations, the agency said.

The late Kim Jong-Il travelled to China four times in less than two years at the end of his life -- underscoring the importance of the relationship between the two countries.

Jang -- the husband of Kim Jong-Il's sister Kim Kyong-Hui -- is seen as a key figure in the North's power elite who supports the young and inexperienced Kim Jong-Un, believed to be in his late 20s.

Powerful North Korean official meets China's Hu
Beijing (AFP) Aug 17, 2012 - A top North Korean official met China's President Hu Jintao on Friday, state media said, in high-level talks which are seen as a precursor to a visit by Pyongyang's young leader Kim Jong-Un.

Hu met with Jang Song-Thaek -- Kim's uncle -- following several days of discussions between the two sides aimed at pushing forward the development of economic zones near the Chinese border, China Radio International (CRI) said.

The talks represent the highest diplomatic exchanges between North Korea and China since Kim Jong-Un assumed power after the death last year of his father Kim Jong-Il.

They are also a sign that Pyongyang and Beijing are strengthening ties after the North Korean leader signalled his intention to improve his country's impoverished economy.

Kim Jong-Un told a visiting Chinese Communist party delegation earlier this month that he was seeking economic development, Chinese state media reported at the time.

Jang Song-Thaek, who is the chief of the Central Committee of the Workers' Party of Korea, met with Hu in Beijing after a series of discussions with China's Commerce Minister Chen Deming.

"Over the years, Jang has done a huge amount of work to help develop friendly relations between North Korea and China, and we greatly appreciate that," said Hu, according to CRI.

Later, the state-run Xinhua news agency quoted Hu as saying that China is prepared to work with North Korea to raise relations to a new level, keep up high-level contacts, bolster cooperation and communicate closely on regional and international issues.

Xinhua quoted Jang, meanwhile, as saying his country is ready to work with China to develop the economic zones and strengthen and expand relations between the countries.

Chinese television showed footage of Jang's meeting with Hu as well as a separate discussion he had Friday with Premier Wen Jiabao.

Talks during Jang's visit focused on two economic zones, Rason, in the northeastern part of North Korea, and Hwanggumphyong and Wihwado, on two islands in the estuary of the Yalu river.

Agreements were signed between the two sides earlier this week covering the establishment and operation of management committees in the zones, China's commerce ministry said in a statement.

They also agreed to cooperate on electricity and agriculture, the ministry said.

China's importance to North Korea was highlighted by Kim Jong-Il travelling to China four times in less than two years at the end of his life. His last visit came in August 2011, just months before his death in December.

China is the only major ally as well as main trade partner of North Korea, a heavily militarised country that has carried out underground nuclear explosions and ballistic missile tests yet struggles to feed its people.

North Korea's reliance on China, with which it shares a border, has increased as international sanctions over its missile and nuclear programmes restrict its ability to secure international credit and trade.

Jia Qingguo, professor at Peking University's School of International Studies, said that Jang's visit this week comes amid signs North Korea is carrying out reforms.

"China has always been a supporter of North Korean reforms," Jia said, emphasising that Beijing is likely to increase such backing if it turns out Pyongyang is pursuing them.

"At the same time, China would try to persuade it to give up its nuclear weapons programme," he said.