Internet.org, the project Facebook set up to expand Internet access in poor parts of the world, has been hobbled in India by accusations that it prevents fair competition online.

Several major Indian Internet companies criticized or withdrew from a part of the project that makes certain online services available for people to use without incurring data charges, a practice known as “zero rating.” The companies moved against Facebook after hundreds of thousands of Web users joined a campaign accusing the company of breaching net neutrality, the principle that Internet service providers should not treat various online services differently.

On Wednesday, broadcaster NDTV said it was withdrawing from Internet.org’s zero rating program. The Times Group, India’s largest media company, said it was withdrawing some of its sites immediately and would pull the rest if other companies followed its recommendation to pledge against zero rating.

The travel site Cleartrip and the news aggregator Newshunt also withdrew their participation from Internet.org. Flipkart, India’s largest online shopping site, said on Tuesday that it had pulled out of a zero rating scheme run by the Indian mobile operator Airtel and would not participate in any such programs in the future.

A campaign group called Net Neutrality India says that six of the 38 sites included in Internet.org’s zero rating program have now withdrawn. A Facebook spokeswoman, Jennifer Hanks, declined to comment. The company’s CEO, Mark Zuckerberg, wrote an article in the Hindustan Times today disputing the suggestion that zero rating compromises net neutrality. “Internet.org doesn’t block or throttle any other services, or create fast lanes,” he wrote.

Internet.org was started by Zuckerberg in 2013. His company works with governments, telecom providers, and other companies to improve physical infrastructure and cut the cost of Internet connections. Its most visible activity, though, has been zero rating: thanks to deals struck with mobile operators in India and elsewhere, people can access certain sites through an Internet.org mobile app without any data charges. (Facebook says it does not cover the cost of the customers’ data usage—implying that carriers eat the charges in hopes that more people will come online and eventually pay.) The sites that are available vary from country to country, but they always include Facebook, Wikipedia, and international and local news sites. The program is live in six countries, and Facebook says it is accessible to 800 million people.

The social network did not invent the idea of zero rating, which critics have long said distorts fair competition, discriminating in particular against new, local Internet companies (see “Around the World, Net Neutrality Is Not a Reality” and “Facebook’s Two Faces”). However, since Internet.org launched zero rating in India in February, those criticisms have gained wider public support. Net Neutrality India said today that a tool on its website had been used to send more than 700,000 e-mails of complaint about zero rating to the Indian telecommunications regulator.

“A rapidly growing number of Indian firms have publicly affirmed that they stand by strong net neutrality,” says Raman Jit Singh Chima, Asia lead for the nonprofit Access Now. “They should be congratulated for reconsidering their involvement in zero rating partners [and] committing to have net neutrality protected in law in India.” Regulators in the Netherlands, Slovenia, Brazil, and Chile all ban zero rating under net neutrality rules, says Chima.

Similarly, Netflix said Wednesday it had canceled deals it had with two Australian ISPs to exempt its service from data caps, saying it was a mistake and contrary to the company’s stance on net neutrality.

But Facebook is not alone in thinking that zero rating can be compatible with a respect for net neutrality. The foundation behind Wikipedia runs a zero rating program in more than 60 countries. A Brookings Institution report that reviewed the effects of various policies intended to widen Internet access in poor parts of the world concluded that zero rating was one of the best. “There is evidence that zero rating can mitigate the digital divide,” says Darrell West, who authored the report. “In the developing world, high costs represent one of the most important barriers to Internet access.”

West says zero rating shouldn’t be seen as harmful to local Internet services. It fuels greater appetite for Internet use overall, and most zero rating plans include both local and global content, he says. “If you combine zero rating with [free municipal] Wi-Fi access, it generally gives people diverse Internet offerings,” he adds.