When Google teamed up with Verizon on Monday to announce a set of proposed rules to govern Internet access, Google’s former allies in the years-long campaign for net neutrality were among its most vocal critics.

A slew of public interest groups that, along with Google, are part of the Open Internet Coalition, slammed the company for putting together a proposal that they said betrayed net neutrality principles. Other Internet heavyweights that are part of the coalition, like Amazon and eBay, appeared to be concerned with Google’s compromise, but were less vocal about it.

On Wednesday, Facebook became the most prominent Internet company to part ways with Google. In a statement, Facebook, which is also part of the coalition, suggested that exempting wireless networks from net neutrality rules, as proposed by Google and Verizon, was the wrong approach.

The company said: “Facebook continues to support principles of net neutrality for both landline and wireless networks. Preserving an open Internet that is accessible to innovators — regardless of their size or wealth — will promote a vibrant and competitive marketplace where consumers have ultimate control over the content and services delivered through their Internet connections.”

On Monday, I spoke with Matt Cohler, one of Facebook’s earliest employees and now a venture investor at Benchmark Capital. His concerns were broader than just wireless networks, which he said should be protected, too. Mr. Cohler said he was disturbed by the division that Google and Verizon seemed to have drawn between the public Internet, which would be subject to net neutrality principles, and new “enhanced services,” which would be free of such rules. “It is certainly concerning to me that there is language being used about the ‘public Internet,’” Mr. Cohler said. “That begs the question about what is not the public Internet.”

Google has vehemently rejected the notion that its joint proposal with Verizon betrays net neutrality principles. Eric E. Schmidt, the company’s chief executive, said that Google continued to believe that an open Internet, where broadband providers cannot prioritize the traffic of certain companies, remained essential to preserve innovation on the Web. “The next two people in a garage really do need an open Internet,” he said.

The proposal by Google and Verizon has its supporters. A series of legal and technology experts have been laying out arguments for and against it in an online debate on nytimes.com.

The other large Internet companies that have spoken out on the Google-Verizon proposal have been more oblique than Facebook in laying out their concerns.

In a statement, eBay said that it “believes that openness on the Internet is the right policy for Internet businesses and Internet users, and that two-tier networks with corporate toll lanes would stifle ground-up innovation and benefit dominant businesses at the expense of smaller competitors and entrepreneurs.” It added: “We will review the recent suggestions from Google/Verizon while remaining focused on supporting the openness of the Internet so that it continues to promote innovation, entrepreneurship and empowerment for all.”

Paul Misener, vice president of global public policy for Amazon, said in a statement: “We’ve long supported net neutrality, and although we agree that network operators should be allowed to offer additional services, we are concerned that this proposal appears to condone services that could harm consumer Internet access.”