(Reuters) - Smithfield Foods Inc (>> Smithfield Foods, Inc.) shareholders on Tuesday approved the pork giant's $4.7 billion sale to Shuanghui International Holdings Ltd (>> Henan Shuanghui Investment & Development) in what is shaping up as the biggest acquisition of a U.S. company by a Chinese firm.

The closely watched transaction, valued at $7.1 billion including debt, is expected to close by September 26.

The deal, which aims to satisfy China's increasing appetite for pork, marries two of the world's largest pork producers and had faced scrutiny over China's high-profile food safety failures, concerns over U.S. pork supplies and U.S. national security.

But earlier this month, the U.S. Committee on Foreign Investment cleared the way for the deal, removing an important hurdle.

More than 96 percent of the votes cast at a special Smithfield shareholder meeting on Tuesday were in favor of the acquisition. The votes cast represented 76 percent of Smithfield's outstanding common shares, the company said in a statement.

Under the terms of the deal, Smithfield shareholders will receive $34 cash for each share of Smithfield common stock they own.

Shares in Smithfield were unchanged at $33.98 in midday trading.

(Reporting by Lisa Baertlein in Los Angeles; Editing by Gerald E. McCormick and John Wallace)