Although China's growth is expected to slow from the current high rate, it will surpass the United States based on purchasing power parity by 2050 and lead seven other emerging countries to overtake the Group of Seven, or G7, as the world's biggest economic bloc, the report said.

Purchasing Power Parity, or PPP, is a currency conversion measure that uses a common currency and equalize the purchasing power of different currencies. In other words, the PPP eliminates the differences in price levels between countries in the process of conversion.

The Emerging Seven economies, or E7 as the PwC coined it, will by 2050 be around 25 percent larger than the current G7 when measured in US dollar terms at the market exchange rates or around 75 percent larger in PPP terms.

The E7 includes "BRIC" - Brazil, Russia, India and China - plus Indonesia, Mexico and Turkey.

In contrast, the E7 is currently only around 20 percent the size of the G7 at market exchange rates and around 75 percent of its size in PPP terms.

"China and India are the two important markets to drive up the E7 economies," said John Hawksworth, head of the macroeconomics unit of PricewaterouseCoopers based in London, and the author of the report, in Shanghai.

China, despite its projected slowdown in market growth, is forecast to be around 95 percent the size of the United States at market exchange rates by 2050 or about 40 percent larger in PPP terms.

China's economy expanded 10.2 percent in the first quarter after soaring 9.5 percent last year.

Growing rapidly as a major player, China is also burdened with some problems which may hinder its growth.

The declining working age population, or those between 16 years and 50 years, will be one disadvantage for China while India, a relatively young economy, will gain from its growing working population.

Better education, higher energy efficiency and the development of the country's financial sectors are suggestions offered for a healthy economic expansion.

"China needs to diversify its capital markets besides focusing on the banking sector," he said, adding that the securities and corporate bond sectors are areas where expansion is pending.