The top US military officer said Monday that Washington's armed presence in the Asia-Pacific was meant to contribute to regional stability as he met his Chinese counterpart on a rare visit.

General Martin Dempsey, chairman of the Joint Chiefs of Staff, was in Beijing amid regional tensions over North Korea's nuclear programme, maritime disputes and China's concerns that the US wants to contain its growing military strength.

Relations between Washington and Beijing have also been strained over a US "pivot" to Asia after years of conflict in Iraq and Afghanistan and accusations, denied by China, that its military has carried out large-scale cyber-attacks on US companies and institutions.

"We seek to be a stabilising influence in the region", Dempsey said at a joint news conference with Fang Fenghui, the chief of the People's Liberation Army general staff.

"We are committed to building a better, deeper more enduring relationship," he said.

Fang said the two militaries needed to deepen cooperation and exchanges.

"The Pacific Ocean is wide enough to accommodate us both," he said. "We should be cooperating partners regardless of the circumstances."

He reiterated China's position that it opposed cyber attacks and was itself a victim.

"Cybersecurity, if it is uncontrolled, the effects can be, and I don't exaggerate, at times no less than a nuclear bomb," he said.

He said China was opposed to nuclear tests by North Korea and supported UN Security Council resolutions against Pyongyang, but reiterated Beijing's position that dialogue was the key to solving the issue.

"North Korea has already conducted a third nuclear test, and it could conduct a fourth nuclear test," he said, though did not elaborate.

Dempsey's predecessor, Admiral Mike Mullen, visited China in 2011 in what was the first trip by a US chairman of the Joint Chiefs of Staff in four years.

The latest visit came as China appeared to single out the US in a military white paper last week, saying that "certain efforts" to enhance military deployment in Asia "are not conducive to the upholding of peace and stability in the region".

China and some of its neighbours, including the Philippines and Vietnam, have boosted their naval capacity amid smouldering spats over disputed regions of the South China Sea, and China put its first aircraft carrier into service last year.

Beijing is also locked in a bitter dispute with Tokyo over islands in the East China Sea.

The US stations tens of thousands of troops in allies Japan and South Korea and has announced plans to deloy more forces in Australia.

China has repeatedly asserted that it does not have an expansionist foreign policy as it continues its "peaceful rise".