As Manmohan Singh, India’s prime minister, wound up his three-day trip to China on Tuesday, the growing trade imbalance between the two countries in favour of Beijing has proved to be one of the most contentious issues.

Sino-Indian trade last year soared 56 per cent to $38.7bn (€26bn, £19.6bn), according to Chinese data, and could reach $60bn by 2010. But this is heavily tilted in China's favour, with the deficit more than doubling to $9.17bn in the past fiscal year.