UPDATE 3-Powerful uncle of North Korea leader in China to talk business

* Visit could signal new North Korea interest in economy

* North Korea highly dependent on China but has resisted

changes

* US urges North's leadership to change course

SEOUL, Aug 13 (Reuters) - North Korean leader Kim Jong-un's

uncle -- the man seen as the power behind the young and untested

dictator -- went to Beijing on Monday in the latest signal that

the reclusive state is looking seriously at ways to revive its

broken economy.

The official KCNA news agency said Jang Song-thaek was

visiting China, the North's only major ally, to discuss setting

up joint commercial projects. The news comes after leader Kim

recently told Beijing that his priority is to develop his

impoverished country's decaying economy.

Last month, a source with ties to both Pyongyang and Beijing

told Reuters the North was gearing up to experiment with

agricultural and economic reforms after Kim and his powerful

uncle purged the country's top general for opposing change.

"A delegation of the DPRK-China Joint Guidance Committee

Monday left here for Beijing, China to take part in the third

meeting of the committee," KCNA said.

DPRK is short for the North's official name, the Democratic

People's Republic of Korea.

"It was headed by its DPRK side Chairman Jang Song Thaek who

is a department director of the Central Committee of the

Workers' Party of Korea."

KCNA said the meeting is to discuss the joint economic

projects in Rason on the North's east coast, and in

Hwanggumphyong, an area on the border between the two countries

that is yet to be developed.

The dispatch gave no details about the projects or who else

was in the delegation.

The visit by Jang, who has long advocated economic reforms

in one of Asia's poorest states, follows growing speculation

that Pyongyang and its new leaders want to bring changes to the

way the economy is managed.

The two countries have planned to develop a new industrial

district on the Yalu River that runs along their border, but the

construction of a new bridge that will be part of the project

has been suspended because of disagreements on how to proceed.

China is believed to be wary of pursuing a major new

commercial venture with North Korea amid its own leadership

transition and as Pyongyang continues to defy calls to divert

scarce resources away from arms development program.

South Korea is the only other partner in commercial

development in the North, with an industrial park just north of

their heavily fortified border that is the site of factories

where about 120 South Korean firms use cheap local labor to make

goods.

But South Korea's Hyundai conglomerate has learned the risks

of doing business with the North after assets it built in the

Mount Kumgang resort on the east coast were frozen following

the shooting death of a visitor in 2008 that led to the

suspension of tours there.

CONTRASTING IMAGE

North Korea already relies heavily on China to support its

crumbling economy but its leadership has in the past proven

deeply suspicious of any changes, seeing them as a threat to its

control over the country.

But Kim Jong-un, who took over the state's family

dictatorship when his father died in December, has presented a

sharply contrasting image to his father and is believed to be

planning to carry out economic and agricultural reform.

"There is an element of explaining to China the reforms and

opening that Kim Jong-un has been planning, and of seeking

support by China, which will be crucial" said Yang Moo-jin of

University of North Korean Studies in Seoul.

In Washington, a senior U.S. official said Jang's visit,

which follows a trip to North Korea earlier this month by a

senior Chinese Communist Party official, also contained an

important element of diplomacy.

It could be a prelude to a mission by new leader Kim to

Beijing, said the official, speaking on condition of anonymity.

"It's also part of refurbishing the relationship, which was

a bit dented" by North Korea's decision to go ahead with a

rocket launch despite public warnings from China, the official

said.

The destitute, centrally planned North Korean economy has

been on the decline for years and is unable even in years of

good harvests to feed its 24 million people.

The problems have been compounded by United Nations

sanctions imposed after Pyongyang's missile and nuclear tests in

defiance of international warnings including disapproval by its

ally China.

U.S. State Department spokeswoman Victoria Nuland urged

China to persuade the new North Korean government to take

actions to end the isolation Pyongyang brought upon itself with

those nuclear and missile tests.

"We're hopeful that the new leadership will consider

changing course," she said.

"They can open their country, come back into compliance and

live in a place that respects human rights, respects the needs

of their people, or they can keep doing what they've been doing

and continue to face isolation and continue to face misery," she

told a news briefing.

In another sign that Kim may be looking to end international

isolation, he has sent the country's nominal head of state Kim

Yong-nam this month to Vietnam and Laos, where he was reported

to have discussed economic development.