CHINA - China's weekend reform of its currency regime nails shut the coffin on the last remains of doubt about whether the world's second-biggest economy has successfully steered a course past a hard economic landing.

Investors were questioning whether the worst sequential slowdown in China's economy since the 2008-09 global financial crisis could enter a sixth quarter after data last Friday revealed the weakest three months of annual growth in three years and a run rate below the official 7.5 per cent 2012 target.

Shifting the yuan trading rules is about the strongest signal Beijing could give that growth downside has diminished and potential pitfalls are manageable.

Few reforms are as replete with risk as tinkering with the currency because faith in its soundness correlates directly with economic stability.

"For everybody who thought China was heading for a hard landing, it's over.

"This move says they are comfortable with the direction the economy is moving in," Mr Paul Markowski, president of New York-based MES Advisers and a long-time investment adviser to China's monetary authorities, told Reuters.

International investors are certainly in need of something to calm concerns about the health of the global economy after asset markets worldwide were rattled last Friday by a combination of below-par Chinese growth data and renewed fears of contagion risks in the debt-plagued euro zone.

Timing, politics and diplomacy are all in focus after last Saturday's milestone step towards turning the yuan into a global currency that doubled the size of its trading band against the dollar to 1 per cent.

But the economics of the move, predicted by a Reuters poll four weeks ago, are the most crucial for the 200 million or so jobs in China's vast factory sector that analysts estimate depend directly on foreign trade.

The reform says Beijing is comfortable with the yuan's value and that exporters have sufficient strength to cope with the government relaxing its grip. As the financial crisis deepened in 2008, China squeezed tightly on the yuan to shield the economy as international trade ground to a halt.