Starbucks Corp. is buying the rest of its East China joint venture in a $1.3 billion transaction, marking the biggest deal ever for a company that sees China as a huge growth opportunity.

The Seattle-based coffee chain will acquire the remaining 50 percent of the business from partners President Chain Store Corp. and Uni-President Enterprises Corp. Starbucks also is divesting its 50 percent stake in a separate joint venture in Taiwan, according to a statement Thursday.

The move underscores Starbucks¡¯ bet that China will be one of the company¡¯s top sales drivers in coming years. It¡¯s wagering that the nation¡¯s growing middle class and urbanization will give it a huge population of potential coffee drinkers to tap.