US President Barack Obama has arrived in Japan for the first stop on an eight-day Asian tour aimed at boosting economic growth.

The first Asian tour of his presidency will also take him to Singapore, China and South Korea and includes an Asia-Pacific Economic Cooperation summit.

He said before leaving that he would be pursuing a growth strategy "that is both balanced and broadly shared".

Earlier, he told Reuters news agency China was a "partner" as well as rival.

In the same interview he warned of "enormous strains" in relations between the world's two most powerful nations if economic imbalances between them were not corrected.

Climate change, the North Korean and Iranian nuclear disputes and US strategy in Afghanistan are also likely to be on the agenda for his talks with Asian leaders.

Mr Obama spent several years in Indonesia as a child and is seen as the first president with an "Asia-Pacific orientation", the BBC's Kim Ghattas reports from Washington.

He will try to capitalise on this as he seeks to build on and improve crucial relationships with allies and rivals across the Pacific, our correspondent adds.

Friction with Tokyo

In Tokyo, the US president will deliver a key speech during which he is expected to reaffirm the strength of Washington's alliance with Japan.

He will also meet Emperor Akihito and Empress Michiko, who have just celebrated 20 years on the throne.

There is some concern in both countries about a drift in relations between the two strong allies.

Recently-elected Prime Minister Yukio Hatoyama campaigned on a pledge to set a more independent course from the US and there has been friction over plans to relocate the US military base on Okinawa.

Japanese peace activists demonstrated near the US embassy in Tokyo on Thursday against plans to move the base to another part of the island and also criticised Mr Obama for not taking time to visit Hiroshima and Nagasaki on his first presidential visit to Japan.

Mr Obama said he would visit the sites of the first atomic bomb attacks on another occasion.

China's growing economic and military power and its effect on relations with Washington are also concerns for some Japanese.

Three days of the tour are being devoted to the Chinese leg during which Mr Obama hopes to discuss a revaluation of the Chinese currency.

He is also set to discuss opening Chinese markets further to US goods and encouraging Chinese consumers to spend more.

China signalled on Wednesday that it might allow an appreciation of the yuan.