Earlier this month a number of U.S. senators urged the Obama administration to consider whether the proposed $4.7 billion deal posed a threat to the U.S. food supply that could justify blocking it.
Other lawmakers had raised the question of Chinese restrictions on U.S. meat imports.
"China's quality management of pork imports and Shuanghui's purchase of Smithfield are totally unrelated to U.S. food safety," Commerce Ministry spokesman Shen Danyang said in a statement on its website, www.mofcom.gov.cn.
"Saying that China prohibits U.S. pork imports is not true," Shen added. "We hope the U.S. will treat the merger case fairly and properly."
He noted that China is a major importer of U.S. meat and only bans imports of pork containing ractopamine, a feed additive used widely in the United States to produce leaner meat.
Shuanghui's purchase of Smithfield, the world's largest pork producer and processor, would be the biggest takeover of a U.S. company by a Chinese firm.
The companies have filed the deal with the Committee on Foreign Investment in the United States (CFIUS) which reviews foreign investment for any potential threat to national security.
