Huawei's efforts to jump into the U.S. smartphone market took a huge hit after AT&T reportedly scuttled plans to sell the Chinese company's devices on the eve of their announcement.

The companies were expected to detail their agreement — Huawei's first with a major American carrier — on Tuesday at the annual CES event in Las Vegas, but The Wall Street Journal reported Monday that AT&T had backed out of the deal.

The paper added it was unclear what prompted AT&T to walk away. The carrier declined to comment, while a Huawei spokesman added only that the tech giant "has proven itself by delivering premium devices with integrity globally and in the U.S. market."

Huawei is the world's No. 3 smartphone maker but only has a scant presence in the U.S. market due to a lack of agreements with domestic carriers.

Last month, Huawei said it planned to dramatically bolster its presence in the country by selling "our flagship phone, our product, in the U.S. market through carriers next year."

The company's U.S. ambitions were previously hindered by a 2012 congressional report that labeled Huawei and fellow Chinese tech company ZTE as national security threats due to their ties to Beijing and potential to spy on Americans.

Huawei alleged that the report was politically motivated, and a company official last month praised the company's emphasis on security.

"They are lying," Richard Yu, who heads Huawei's consumer business, told the Associated Press. "We are a company that really cares about cybersecurity and privacy protection. We do a lot better than the other vendors."