(CNN) — A member of the Senate Intelligence Committee is calling on Apple and Google to remove TikTok from their app stores over concerns about national security, in the latest indication of mounting scrutiny on the short-form video app from members of Congress.

In a letter sent to the two tech giants on Thursday, Colorado Democratic Sen. Michael Bennet calls TikTok "an unacceptable threat to the national security of the United States" and cites the same concerns that have prompted the federal government and more than half of US states to restrict TikTok from official devices and networks.

Writing to Apple CEO Tim Cook and Google CEO Sundar Pichai, Bennet highlighted fears that China could use its national security laws to force TikTok or its parent, ByteDance, to hand over the personal information of the app's US users. The laws in question, Bennet wrote, require organizations in the country to "cooperate with state intelligence work" and to allow the government to access company resources. ByteDance's founder is Chinese and the company has offices in China. TikTok has also disclosed to European users that their data may be accessed by employees based in China.

China could potentially try to shape what US users see on the app, Bennet warned, with possible implications for foreign policy and democracy.

"We should accept the very real possibility that [China] could compel TikTok, via ByteDance, to use its influence to advance Chinese government interests," Bennet wrote, "for example, by tweaking its algorithm to present Americans content to undermine U.S. democratic institutions or muffle criticisms" of China's handling of Hong Kong, Taiwan or ethnic minorities.

Apple and Google didn't immediately respond to a request for comment.

"Unfortunately, Senator Bennet's letter relies almost exclusively on misleading reporting about TikTok, the data we collect, and our data security controls," said Brooke Oberwetter, a TikTok spokesperson.

TikTok CEO Shou Zi Chew is expected to testify before a House committee in March to discuss the company's data security practices.

There is no evidence that the type of spying or manipulation US officials fear has actually occurred, but security experts have warned that it is a possibility.

TikTok has denied that it would ever hand over US user data to the Chinese government. It has increasingly moved to wall off its US operations from the rest of its business, technologically and organizationally — part of what the company has described as a good-faith effort to address the national security concerns.

In her statement, Oberwetter said Bennet's letter "ignores the considerable investment we have made through Project Texas — a plan negotiated with our country's top national security experts—to provide additional assurances to our community about their data security and the integrity of the TikTok platform."

TikTok has spent years negotiating a potential national security deal with the US government that would seek to resolve some of the concerns, but the talks have been mired by delays, leading to frustration among some members of Congress. In recent months, multiple US lawmakers have introduced bills that would ban TikTok from all US devices, including personal ones.

Some other US officials have also called on Apple and Google to voluntarily remove TikTok from their app stores.

Last year, Brendan Carr, a commissioner at the Federal Communications Commission, wrote a letter to the companies urging them to de-list TikTok. The FCC does not regulate app stores, but Carr has said that his agency's experience dealing with Chinese telecom companies has informed his views on the matter. The FCC has moved to block Chinese firms including Huawei and ZTE from the US market, over fears that their wireless networking equipment could be used to collect information on US communications.

Although the leading members of the Senate Intelligence Committee, Virginia Democrat Mark Warner and Florida Republican Marco Rubio, have also been outspoken critics of TikTok, the two lawmakers had not been invited to co-sign Bennet's letter before it was sent, according to a spokesperson for Bennet. Rubio is an author of one of the bills seeking to ban TikTok from the United States, while Warner has said he would prefer to see a bill that targets a broader category of worrisome apps, rather than a single app such as TikTok.

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