US President Barack Obama has said the US welcomes China's rise but that engagement with its government would not come at the expense of its Asian allies.

Mr Obama arrived in Tokyo today at the start of a four-nation trip that comes at a time of rising tension in the region.

The US has urged Japan's unpredictable neighbour North Korea not to conduct another nuclear test.

Mr Obama, who is making the first full state visit to Japan by a US President since 1996, must assuage worries by Japan and other allies that his commitment to their defence in the face of an increasingly assertive China is weak, without hurting vital US ties with Asia's biggest economy.

Mr Obama and Japanese Prime Minister Shinzo Abe are also keen to show progress on a two-way trade pact seen as critical to a broader regional deal that would be one of the world's biggest trade agreements and is central to Mr Obama's "pivot" of military, diplomatic and trade resources towards Asia.

The US President also noted that China and the US could work together on issues such as North Korea's nuclear programme.

He told Japan's Yomiuri newspaper: "We welcome the continuing rise of a China that is stable, prosperous and peaceful and plays a responsible role in global affairs."

"And our engagement with China does not and will not come at the expense of Japan or any other ally."

Such assurances are expected to be high on the agenda when Mr Obama meets Mr Abe at a symbolic summit tomorrow.

Japan, whose relations with rival China have chilled over the past two years, has been beset by anxiety over the degree to which reality matches rhetoric in Mr Obama's promised "pivot".

China, for its part, fears the US is pursuing a policy of containment through its network of Asian allies, several of whom have long-standing territorial disputes with China in the East and South China Seas.

Wednesday's Xinhua commentary criticised US policy in the region as "a carefully calculated scheme to cage the rapidly developing Asian giant".

"The United States should reappraise its anachronistic hegemonic alliance system and stop pampering its chums like Japan and the Philippines that have been igniting regional tensions with provocative moves," it said.