China may pip US to the top economy post by 2030: World Bank

China could overtake the US as the largest economy in the world if it is able to maintain annual growth of 8 per cent over the next 20 years, according to the World Bank's chief economist.

China overtook Japan as the number-two economy last year and for 2011 it is aiming for a growth target of 8 per cent. It is aiming for 7 per cent annual growth from 2011 to 2015.

"China may become the largest economy in the world by 2030," Justin Lin told an economic forum on China development in Hong Kong yesterday, saying its economic size may then be twice as large as the US, measured on the basis of purchasing power parity.

He added that China had been the fastest-growing nation in the world over the past two decades and it grew at a ''miracle'' annual 10.4 per cent growth rate in the 1990-2010 period, which was in sharp contrast with the performance of other transitional economies.

Warning however, that the expansion may be slowed by a weak global recovery from the financial crisis, he urged the country to deal with internal challenges such as tackling the increasing income disparity.

He added global warming would pose a "real challenge" to China's long-term sustainability, but urged that the biggest polluter in the world seize the initiative to turn itself into a new green technology leader.