China Thursday stressed its intention to become a "maritime power" in line with its economic clout, as US President Barack Obama prepares to return to Asia amid regional anxiety at Beijing's rise.

Against a backdrop of simmering territorial disputes with its neighbours, President Hu Jintao indicated China would continue to assert its disputed claims to maritime territories as he addressed the ruling Communist Party's congress.

"We should enhance our capacity for exploiting marine resources, resolutely safeguard China's maritime rights and interests, and build China into a maritime power," Hu said in his speech to more than 2,200 delegates in Beijing.

His comments were likely to fuel alarm among China's neighbours, some of whom have watched warily as Beijing builds up its military amid offshore disputes.

Beijing's sovereignty row with Tokyo over Japanese-controlled islands in the East China Sea has chilled relations, while tensions with the Philippines and Vietnam have flared in the South China Sea.

Japan urged China to use its sea power peacefully.

"It is not surprising to hear leaders in (China) speak about their intention to engage in maritime activities," said a foreign ministry spokeswoman in Tokyo.

"But those activities must be carried out in a peaceful manner based on international law."

Hu said China was committed to a peaceful foreign policy but must continue a military build-up that has seen huge sums poured into developing fighting capacities.

Citing "interwoven problems affecting its survival", he said China must build a "strong national defence and powerful armed forces that are commensurate with China's international standing".

Hu called for China in particular to step up the military's technological abilities, saying its most important task was to be able to "win a local war in an information age".

Military analysts say China's armed forces are far weaker than those of the United States and will remain so for some time.

But there is concern in Asian countries over Beijing's military intentions, worries likely to loom in the background of an East Asian summit in Cambodia this month.

The newly re-elected Obama, who has refocused America's strategic attention on the Pacific in a policy seen by many in China as a challenge, is expected to attend the meeting.

Michael Pillsbury, former head of policy planning for the US Defense Department, told AFP he was surprised by Hu's comments.

"China is entitled to a legitimate military modernisation programme, but the US and the neighbours still cannot get a straight answer about how large Beijing's new navy will be," he said.

"Now President Hu seems to be calling for a major buildup, but again he gives us no details."

China is developing a wide range of new weapons, putting its first aircraft carrier -- a retrofitted hull purchased from the Ukraine nearly a decade ago -- into active service in September. It unveiled its second stealth fighter earlier this month.

The 300-metre (990-foot) carrier "Liaoning" is now preparing for its first take-offs and landing, state press reports said recently.

The party congress meets every five years. This year's gathering will end with confirmation of a new slate of party and national leaders for the next decade, widely expected to be headed by current Vice President Xi Jinping.

During his speech, Hu also warned that China would "never allow anyone or any force to separate Taiwan from the motherland by any means".

Beijing still claims the independently governed island -- separated from mainland China at the end of the Chinese civil war in 1949 -- and accuses the United States of interfering in the situation.

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