US mistakes are the root cause of the global financial crisis, a senior Chinese central bank official said overnight, rejecting criticism of China's high savings rate and booming trade surplus.

"Errors made in US economic policy-making, financial supervision and markets are the ultimate causes of the crisis," said Zhang Jianhua, research head at the People's Bank of China, in an opinion piece carried by the People's Daily.

Some observers in the West are blaming China and other nations' high savings rate and trade surplus for fuelling excess consumption and asset bubbles in the United States, he said.

"Such views are ridiculous and irresponsible in the extreme," Mr Zhang wrote in the harshly worded piece in the Communist Party's mouthpiece.

China's trade surplus rose by $US39 billion ($59 billion) in December, the second largest monthly growth yet recorded, after exports fell but imports fell even sharper.

The figure suggests China's full-year trade surplus was $US295 billion, up about 13 per cent from 2007, rising to a level comparable with the entire economies of Iran or South Africa.

The trade surplus was a main factor in boosting China's forex reserves, the world's largest, which stood at $US1.95 trillion at the end of December, up from $US1.91 trillion three months earlier, official data showed.

China spends a large part of its forex reserves buying US debt, keeping interest rates down and creating the conditions for more spending by American consumers, economists have argued.

But Mr Zhang said China's forex reserves as well as investment in US Treasury bonds started to grow fast only from 2003 while household savings and the long-term interest rate in the United States have been falling since the 1980s.

It was the loose monetary policy, lax supervision and huge fiscal deficit in the United States that caused the financial turmoil, he argued.

The big US trade deficit is a result of its own economic structure, according to the article.

"Theories that try to shift the responsibility for the crisis to countries with high savings are severely lacking in self-criticism, which is urgently needed if we are to... prevent similar crises," Mr Zhang said.