China’s president, Hu Jintao, underlined his country’s growing impact on the world economy at a summit of Asia Pacific leaders today, launching a broadside attack on protectionism in a thinly-veiled barb at the United States.

He also damped down any optimism over the pace of global recovery, saying that the inherent problems of the international economic system had not been fully addressed and that “a comprehensive world economic recovery still faces many uncertainties and destabilising factors”.

Both aspects of his speech, which skated around the issue of China’s own contentious currency policies, were taken by delegates in Singapore as a “curtain raiser” message for Washington — especially for President Barack Obama, who joins Mr Hu in Singapore tomorrow.

Mr Hu’s comments come as tension is visibly mounting between China and the United States on a variety of trade and policy issues. Mr Obama’s first visit to Beijing, scheduled for next week, is likely to see the two leaders clash over the question of whether China’s currency is unfairly undervalued and causing trade distortions between the two giant economies.

Washington and Beijing have, in recent weeks, exchanged tit-for-tat gambits: the US has imposed tariffs on tyres and steel pipes, while China has launched an anti-dumping investigation into the major US carmakers.

Even before those trade spats broke out, China’s sense of frustration had been growing: the country is an increasingly aggressive competitor in the global quest for resources, but attempts by its firms to invest in resources have been politically thwarted around the world.

“We must continue to promote trade and investment liberalisation and facilitation and oppose protectionism in all its manifestations, particularly the unreasonable trade and investment restrictions imposed on developing countries,” Mr Hu said.

His speech called for efforts to conclude the Doha round of negotiations on trade liberalisation — a process that has been deadlocked since 2001 and which appear doomed to remain stalled indefinitely.

But the Chinese president’s speech was also significant for what it did not cover. One of Beijing’s responses to last year’s financial turmoil was to peg its own currency against the US dollar. Earlier this week, China’s central bank hinted that it might edge away from that peg, although other Asia Pacific delegates expressed doubts that this would unfold very quickly. South-East Asian economies are also keen to see the Chinese yuan revalued, because its peg to the falling dollar has made their own exports less competitive.

Also present at the Asia Pacific Economic Cooperation conference was Dominique Strauss-Kahn, the International Monetary Fund chief. He said: “China's economy in the coming years will be focused on domestic growth and the value of renminbi will have to be increased."

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