WASHINGTON — Joseph R. Biden Jr. has been critical of Big Tech, admonishing Facebook for mishandling misinformation and saying internet companies should lose a central legal protection.

But his campaign has quietly welcomed onto its staff and policy groups people who have worked with or for Silicon Valley giants, raising concerns among the industry’s critics that the companies are seeking to co-opt a potential Biden administration.

One of Mr. Biden’s closest aides joined the campaign from Apple,while others held senior roles at firms that consulted for major tech companies. And a nearly 700-person volunteer group advising the campaign, the Innovation Policy Committee, includes at least eight people who work for Facebook, Amazon, Google and Apple, according to documents reviewed by The New York Times. Other committee members have close ties to the companies, including economists and lawyers who have advised them, and officials at think tanks funded by them.

The group’s members also include some prominent progressives arguing for stiffer regulation of tech. But the presence of the industry’s allies inside Mr. Biden’s policy apparatus and campaign and transition teams — and his campaign’s effort to ensure the confidentiality of its policy process — has alarmed an increasingly influential coalition of liberals who say the tech titans stifle competition, disregard user privacy and fail to adequately police hate speech and disinformation.

They are hoping to dissuade Mr. Biden, who has not made tech issues a major focus of his campaign, from following the example of his former boss, President Barack Obama, whose embrace of tech companies helped turn them into darlings in Washington.

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The committee is divided into smaller groups that focus on issues like antitrust policy, artificial intelligence, broadband access, disinformation and data privacy. The antitrust group includes people with tech ties like Mr. Perault, Mr. Raut and Mr. Shelanski. But it also includes some people who have pushed for more scrutiny of the tech giants, including employees at rival companies as well as the activist Sarah Miller and Tim Wu, a professor at Columbia Law School, prominent critics who have called for more vigorous antitrust enforcement. (Mr. Wu is also a contributing opinion writer at The Times.)