Facebook also said that Internet.org is open to all content and application developers who meet "certain guidelines". This follows criticism from free Internet advocates that the social networking site was "hand-picking services" violating principles of net neutrality.
Zuckerberg, who in the past had defended Internet.org, said in his video blog posted Monday, that the programme supports itself.
"When people use free basic services, more of them then decide to pay to access the broader Internet and this enables operators to keep offering these basic services for free. It is not sustainable to offer the whole Internet for free," he said.
But, it is sustainable to offer free basic services that are simpler, use less data and work on all low-end phones, he added.
The net neutrality debate in India was triggered after Airtel introduced an open marketing platform 'Airtel Zero' where the data charges were being borne by application developers. Facebook, which has tied up with Reliance Communications for Internet.org initiative in India, too offer access 33 websites for free.
Free Internet advocates had raised objections to these platforms, saying there were in violation of net neutrality, which stands for equal treatment for all Internet traffic and any priority based on payment to service providers like telecom companies is seen as discriminatory.
Zuckerberg had earlier said principles of neutrality must co-exist with programmes like Internet.org that encouraged bringing people online.
Internet.org aims to bring 5 billion people online and has partnered mobile operators, local entrepreneurs and companies for launching the initiative across various countries, including India.
"A reasonable definition of net neutrality is more inclusive. Access equals opportunity. Net neutrality shouldn't prevent access. We need both. It's not an equal Internet if a majority of people can't participate," he said.