Amazon.com Inc., Google Inc. and more than 100 other software, social-media and technology companies said they oppose a U.S. proposal to let Internet-service providers charge them extra for faster routes to Web users.

The rules may let telephone-service and cable providers “discriminate both technically and financially” and would be “a grave threat to the Internet,” the companies said Wednesday in a letter to the Federal Communications Commission. Other signers included Facebook Inc., Netflix Inc. and Microsoft Corp.

FCC Chairman Tom Wheeler has asked the agency to vote May 15 on whether to begin writing rules to let Internet-service providers such as AT&T Inc. and Comcast Corp. negotiate deals with content makers like Google for quicker and more reliable delivery of video and other fare. Wheeler said last month the idea doesn’t abandon the FCC’s Internet fairness policy, commonly known as “net neutrality.”

The companies in the letter Wednesday disagreed, saying the FCC should protect users and content makers from service providers blocking Web traffic or seeking payment for better handling. The letter was addressed to Wheeler and the four other FCC commissioners, and distributed by e-mail.

The FCC had no immediate comment on the companies’ letter, Neil Grace, a spokesman for the agency, said in an e-mail.

A court in January threw out FCC rules designed to ensure Web traffic is handled fairly, and the agency is seeking new measures. The vote next week is to commence a comment period, and Wheeler has said he wants a final decision this year.

Vote Delay

Advocacy groups including Public Knowledge and Free Press that have supported rules to prevent Internet-service providers from unfairly blocking or slowing Web traffic said payment arrangements won’t protect Internet users.

FCC Commissioner Jessica Rosenworcel, who like Wheeler is part of the agency’s Democratic majority, Wednesday said she has “real concerns” about Wheeler’s proposal and called for delaying the vote by at least a month. The proposal has unleashed “a torrent” of reaction and “rushing headlong into a rulemaking next week fails to respect the public response,” Rosenworcel said in remarks in Washington.

Mignon Clyburn, a Democratic member of the FCC, in a blog post Wednesday said “over 100,000 Americans” have contacted her or the agency to ask her “to keep the Internet free and open.” Clyburn said that in a previous vote in 2010 she had favored prohibiting payment for fast passage.

‘Collective Voice’

Wheeler will move ahead with the vote next week “to bring us one step closer to putting rules on the books,” Shannon Gilson, an agency spokeswoman, said in an e-mail Wednesday.

The agency’s Republicans have criticized open-Internet rules, saying they represent unnecessary regulation.

Companies signing the letter included Amazon, the largest Internet retailer; Netflix, the biggest online-video subscription service; Microsoft, the largest software maker and Facebook, the largest social-networking site.

Also listed as signing were EBay Inc., the top online marketplace; Yahoo! Inc., the largest U.S. Web portal; and the Twitter Inc. messaging service.

“This letter represents the collective voice of the world’s strongest innovators and demonstrates a shared commitment to meaningful network neutrality,” Alan Davidson, director of the Open Technology Institute at the Washington-based New America Foundation policy group, said in an e-mailed statement.

“The Internet works best when consumers control what they say and do on the connections that they pay for, and the FCC’s rules should protect those connections from discriminatory interference,” said Davidson, a former Google executive.