China's top military officer said Monday the timing of US naval exercises in the South China Sea was "inappropriate," after talks with his US counterpart aimed at cooling the territorial dispute.

General Chen Bingde urged the United States to be "more modest and prudent in words and deeds", amid growing tensions over China's claims in the strategic and potentially resource-rich region.

"On various occasions, the US side has expressed that it does not have the intention to intervene in the disputes in the South China Sea," Chen told reporters after meeting Admiral Mike Mullen in Beijing.

"However, we are observing the latest joint exercises between the US and other countries, for example the Philippines and Vietnam.

"We acknowledge that those exercises were there in the past, however the timing of these joint exercises is inappropriate as we see it."

The Philippines recently finished 11 days of naval exercises with the United States close to the South China Sea, although both sides emphasised the event was an annual one aimed at deepening defence ties.

Vietnam and the United States are to hold joint naval activities this month, with the US Navy again saying they are long-planned and unconnected to recent tensions.

Mullen is the first chairman of the US Joint Chiefs of Staff to visit China since 2007 and his trip comes as military ties between the two powers are tested by Beijing's growing assertiveness in the South China Sea.

Speaking after the pair met on Monday, Chen said they had "found a lot of common ground", but that there were still "different opinions on certain issues."

"The key to developing healthy, stable and reliable military relations is mutual trust, and the pre-condition is mutual respect," he said.

China, the Philippines, Vietnam, Brunei, Malaysia and Taiwan have overlapping claims to parts of the South China Sea, which is believed to have vast oil and gas deposits, while its shipping lanes are vital for global trade.

Vietnam and the Philippines have in recent months accused China of taking increasingly aggressive actions in staking its claims.

In May, Vietnam said Chinese marine surveillance vessels cut the exploration cables of an oil survey ship inside Hanoi's exclusive economic zone.

And Philippine President Benigno Aquino has accused China of inciting at least seven recent incidents, including one in which a Chinese vessel allegedly opened fire on Filipino fishermen.

In response, China has insisted it wants to resolve disputes peacefully but remains firm in its claims to most of the South China Sea, even waters within the Philippines' economic exclusion zone.

Speaking to reporters after arriving in Beijing on Sunday, Mullen said Washington was concerned about freedom of navigation, but expressed hope that the myriad disputes would be "resolved peacefully".

With ties sometimes fraught between the two militaries, he stressed that the US was in no way seeking to contain China's dramatic rise, but said it would remain active in the Asia Pacific region for a long time.

Mullen is also expected to address rising tensions with North Korea and measures to boost security cooperation between China and the United States during his four-day trip.

On Sunday, he urged the Chinese government to use its relationship with Pyongyang to ensure regional stability, while warning North Korea against further dangerous provocations.

He was due to hold talks later Monday with China's vice president Xi Jinping, who is widely expected to take over as president next year, and will visit military bases in the eastern provinces of Shandong and Jiangsu on Tuesday.