Beijing will not act first to "stir up troubles" over island disputes with neighbours, China's defence minister said Tuesday at a meeting with American counterpart Chuck Hagel that was overshadowed by regional tensions.

China and Japan are embroiled in a bitter row over disputed islands controlled by Tokyo in the East China Sea, raising concerns about the possibility of a clash between the Asian powers.

"We will not take the initiative to stir up troubles," General Chang Wanquan told a joint news conference in the Chinese capital.

The ministers' meeting came a day after officers allowed the US Defense Secretary to tour the country's first aircraft carrier, a rare move by the normally secretive People's Liberation Army (PLA).

But despite lip service on dialogue and cooperation surrounding Hagel's trip, which follows a visit to Japan, the press conference highlighted the numerous disagreements between the two countries.

Beijing was ready to resolve disputes peacefully, Chang said, but added that "China has indisputable sovereignty" over the islands involved, calling territorial sovereignty a "core issue" on which "we will make no compromise".

China-Japan relations were in "severe difficulties", he said, expressing hope that Washington could restrain Tokyo and "not be permissive".

Last November Beijing unilaterally declared an air defence identification zone (ADIZ) over the East China Sea, including the disputed islands, prompting US condemnation.

Beijing requires aircraft flying through it to identify themselves and maintain communication with Chinese authorities.

Wagging his finger, Hagel said setting up ADIZs without consulting other governments was risky as it could lead to "misunderstandings" and "eventually get to a dangerous conflict".

Beijing is also involved in disputes in the South China Sea and Hagel reiterated that the US takes no position on territorial issues, wanting the disagreements resolved "peacefully".

But he added the "Philippines and Japan are longtime allies of the United States".

Washington had treaties with both countries and "we are fully committed to those treaty obligations", he said.

- Cyber-warfare -

US officials said the visit to the carrier marked a promising step by the Chinese but the two nations remained deeply divided over the regional territorial disputes, the threat posed by North Korea and cyber-spying, with each side trading accusations of digital espionage.

In his talks Hagel urged authorities to pursue a more open dialogue about cyber-warfare.

"Greater openness about cyber reduces the risk that misunderstanding and misperception could lead to miscalculation," Hagel said.

A senior US defence official who spoke on condition of anonymity said: "We have tried to be as open and transparent on that as we can be. And we would like to see them be able to reciprocate".

But the Chinese so far had not "reciprocated", said the official, confirming a New York Times report.

The US is investing heavily in a new cyber warfare command, and suspects PLA units are behind an increasing number of digital attacks on government and US corporate networks.

But China accuses Washington of waging its own cyber offensive after revelations of far-reaching electronic espionage by the US National Security Agency, including media reports the spy service hacked into telecoms giant Huawei's network.

- 'Great power' responsibilities -

During his Asia tour Hagel has stressed that as a "great power" China has to live up to its "responsibilities", suggesting Beijing should respect its smaller neighbours and adopt a more transparent approach in its relations with the US military.

Hagel "wants to have a frank discussion with Chinese leaders about those responsibilities", the defence official said.

During his two-day visit to Tokyo, Hagel announced the deployment of two additional missile defence ships to Japan to counter the danger posed by North Korea, which recently test-fired medium-range missiles.

Washington has pleaded with China to exert more pressure on its North Korean allies but has come away disappointed.

China showed off its sole aircraft carrier, the Liaoning, to Hagel in the eastern city of Qingdao on Monday, giving him a two-hour tour, including a briefing from the skipper and a walk on the flight deck.

The Chinese bought the Soviet-made warship from Ukraine and refitted it, putting the vessel into service in September 2012 in a milestone for the country's growing military might.

"We didn't see every space aboard the ship but we felt this was an honest, genuine effort" to be more transparent, the official said.

But editorials in state-run media on Tuesday chided the US for inflaming territorial disputes with Japan and the Philippines by siding with those nations.

"There is little difference between Washington's current partiality for Tokyo and Manila and open support of confronting China," said the Global Times.

Many Chinese believed that "the US is attempting to burden China's rise through instigating confrontation with other countries in the neighbourhood", it said.

The China Daily said: "Instead of helping to ease the tensions and promote peaceful settlements of the disputes in the South China Sea, the US has simply been emboldening countries in their bids to provoke China."