US Senator Richard Durbin has written a letter to the Chinese internet firm Baidu seeking information about a potential partnership with the social media giant Facebook.
In the same letter, Mr Durbin appealed to Baidu not to interfere with the freedom of expression of its users by censoring search results.
The Democrat from Illinois released a copy of the letter on Wednesday to the media.
The letter, addressed to the founder and acting Chief Executive of Baidu Robin Li,
states, "I appreciate that Baidu has given millions of Chinese citizens the ability to access information," the AFP reports.
"At the same time, your company has a moral obligation to respect fundamental human rights. This is particularly important in light of the Chinese government's recent crackdown on dissent, including the detention of many Internet activists."
The letter also expressed the senator’s concerns regarding the issue of internet censorship imposed by the company on its users.
“As a member of the U.S. Congress, I am especially concerned about Baidu’s internet censorship because of your company’s extensive business dealings in the United States.” Durbin wrote.
Baidu officials have not reacted officially to this letter.
Durbin is the Democratic Whip, the second highest position in the Senate.