Senator Mark Warner, the top Democrat on the Senate Select Committee on Intelligence, said in a statement Thursday that his office has sent a letter to Google parent company Alphabet requesting information about its partnerships with Huawei and other Chinese companies.
"We look forward to answering these questions," a Google spokesperson said in a statement. "We do not provide special access to Google user data" as part of the agreements the company has with device manufacturers.
A separate, similar letter by Warner was sent to Twitter.
A spokesperson for Republican Congressman Mike Conaway also confirmed he is looking into ties between Google and Huawei. The Wall Street Journal and Bloomberg earlier reported moves by Congress members to look more deeply into Google's relationship with Huawei.
The Senate Intelligence Committee will call on Facebook's Mark Zuckerberg, Alphabet/Google's Larry Page and Twitter's Jack Dorsey to address their data-sharing deals with Chinese device makers if and when they appear before Congress this summer, a Senate source told CNNMoney's Dylan Byers.
Huawei is the world's third largest smartphone maker behind Samsung and Apple. It's also a leading provider of telecom equipment in Asia, Europe and Latin America.
But the company has been the focus of national security concerns in the United States. Intelligence officials have warned that the Chinese government can use Huawei smartphones and other products for intelligence gathering.
Huawei has strongly denied it poses a risk to the United States.
Huawei did not immediately respond to a request for comment Thursday.
In his letter to Alphabet, Sen. Warner says he is aware of "strategic partnerships" between Google and Chinese smartphone makers Huawei and Xiaomi, as well as tech conglomerate Tencent.
"The possibility of Chinese vendors with documented ties to the Chinese Communist Party having access to Facebook's private API (and potentially Alphabet's) — particularly as China develops tools to harness individual-level data for surveillance and social control — raises serious national security concerns," the letter reads.
Xiaomi did not immediately respond to a request for comment and Tencent could not immediately be reached.
A few days ago, Facebook confirmed it provided Huawei access to user data.
Facebook said it has been operating data-sharing partnerships with four Chinese device makers that enabled the companies to recreate Facebook-like experiences for their users.
It was previously known Facebook had such deals with around 60 companies when mobile phones were less powerful and app stores did not yet exist, and the company announced in April it was winding down the partnerships. It said Tuesday that it has ended more than half of them and that its partnership with Huawei will shut down this week.
In his letter to Twitter Tuesday, Warner asks the company whether it has any agreements similar to the ones Facebook has disclosed.
Twitter did not immediately respond to a request for comment.
"There are now indications that this practice of embedding social media sharing functions with Chinese [device makers] may have been more widespread, including potentially through agreements between Twitter and these Chinese companies," he wrote.