The punitive tariffs range from 7 per cent to 46 per cent for five years.

'This was a major trade dispute between the US and China. China handled it in a professional manner. It's an important step in China becoming a responsible member of the World Trade Organisation,' said Edmund Sim, a partner with US law firm White & Case.

'The optical fibre case was one of the most complicated anti-dumping cases taken by the Chinese government. This was raised to a very high level by US politicians,' Mr Sim said.

The ministry said the amount dumped by diversified technology company Corning was very small and exempted it from duties.

Other optical fibre firms in the US, Japan and Korea were not so lucky.

The lenient treatment of Corning prompted suggestions that the central government was 'selling out' to US interests.

However, Mr Sim said Corning deserved its exemption because it co-operated fully with the central government while the companies that received anti-dumping duties did not.

'The Chinese government displayed great professionalism in conducting this case. The quality of Chinese anti-dumping investigations in terms of professionalism and transparency has improved over the past three years,' he said.

Leora Blumberg, international trade adviser at US law firm Heller Ehrman, said China, despite its relative inexperience, had negotiated a complex process impressively.

The ministry's decision could have a profound affect US exports to China, Mr Sim said.

While the US is outsourcing low-end production to China, it is banking on its competitiveness in high-technology exports such as optical fibre to reduce its yawning trade deficit, he said.

Previous mainland anti-dumping action has involved more basic products, such as chemicals and other raw materials.

'That's why it's taken seriously by the US government. Optical fibre is the most technologically advanced product in a Chinese anti-dumping case.'