China expressed worry about reports that North Korea had shelled a South Korean island on Tuesday in the latest escalation of tensions on the Korean peninsula that neighbors the world's second-biggest economy.

A spokesman for the Chinese Foreign Ministry, Hong Lei, told a news conference both sides of the divided Korean peninsula should "do more to contribute to peace", and said it was imperative to return to six-party talks aimed at ending North Korea's nuclear weapons program.

"We have heard reports and express our concern. The situation still needs to be confirmed," said Hong, responding to a question about the North Korean artillery attack.

"China hopes that the relevant parties will do more to contribute to peace and stability in the region," he added.

"It is imperative now to resume the six-party talks."

China is North Korea's only major ally, and its economic and diplomatic support have been important to shoring up its otherwise isolated neighbor, whose leader Kim Jong-il visited China twice this year to strengthen ties.

 

But those ties have become a sore point with Washington after revelations that North Korea appears to have made big steps towards enriching uranium. A U.S. envoy on the issue, Stephen Bosworth, arrived in Beijing on Tuesday.

The stalled six-party talks bring together China, North and South Korea, the United States, Japan and Russia and have sought to end Pyongyang's nuclear weapons development in return for aid.

The impoverished and isolated North depends heavily on its only major ally for economic and diplomatic support and its leader, Kim Jong-il, has visited China twice this year, in part to gain backing for the anointment of his son to eventually take over the family dynasty.

A U.S. academic, Siegfried Hecker, who recently visited North Korea, said at the weekend he had seen more than a thousand centrifuges for enriching uranium during a tour of the North's Yongbyon nuclear complex.