Barclays Capital reiterated its belief that China is a big growth opportunity for Apple Inc. and could be bigger than even the U.S., within a few years.

At a recent visit to Apple headquarters, Chief Executive Tim Cook indicated he is very focused on the growth opportunity in China, said Ben Reitzes, an analyst at Barclays Capital.

On the last weekend of calendar third quarter of 2011, Apple opened seven retail stores in six countries, including the first store in Hong Kong, which helped deliver the highest opening day for Mac sales ever. Reitzes said the Hong Kong store joined five other Apple stores in China as the highest traffic stores and the highest revenue generating stores in the world.

Greater China revenue represented just 2 percent of Apple's sales in fiscal year 2009. However, in fiscal 2011, the region accounted for 12 percent of total revenue, making it Apple's fastest growing major region by far.

In the September quarter alone, China delivered $4.5 billion of revenue or 16 percent of total, up about 270 percent year-over-year, bringing the total revenue for the fiscal year to over $13 billion.

In addition to six retail stores in Greater China right now, Apple's online store opened in the region at the end of 2010. The company is expanding distribution with over 200 mono-branded stores that Apple calls APRs (resellers).

Apple is also now up to over 7,000 point-of-sales on the iPhone in Greater China. The iPhone currently sells officially through carrier, China Unicom, with the 4S going on sale on Jan. 13.

Reitzes believes more carriers (likely third biggest carrier, China Telecom) will be added in China for the iPhone over the next few quarters and that growth in China could drive up to Apple's estimates over the next few years.

In fact, Yiping Huang (Chief Economist, Emerging Asia) and the Emerging Markets Research team, along with colleagues from Equity Research and Asia-Pacific Credit Research teams, recently authored a Barclays Capital Cross Asset Research Piece, predicting China may be at an inflection point with regard to consumer purchasing power.

Huang states China could see further increases in household income and improvements in income distribution that could impact mid/high level consumer goods sectors over the long-term.

Huang forecasts a multi-year, multi-layer wave of consumption upgrading to take place in China in the coming decade, as lower-income/rural/inland households increase demand for mid and high-quality consumer goods and services. This consumption upgrading story will be underpinned by rapid household income growth and the rise of the middle class.

China's middle class, if defined as those with an annual income of 55,000 to 200,000 Chinese yuan - the equivalent of $8,000 to $30,000 - amounted to 135 million households in 2010, according to surveys conducted by McKinsey & Co. in 2011. This number is expected to reach 200 million by 2015.

In particular, upper middle class (annual income of 100,000 to 200,000 Chinese yuan, or $15,000 to $30,000) will rise from 13 million households in 2010 to 76 million by 2015.

Although the luxury goods market is likely to remain strong, colleagues with Asia Ex-Japan Consumer and Asia Ex-Japan Retail Equity Research teams believe the upgrade in Chinese consumption will also create great opportunities in mid- to high-end products over the next five years, with Consumer Discretionary items benefiting more than Consumer Staples on a relative basis.

If accurate, this thesis could bring big benefits to Apple, which continues to grow its footprint in that region.