After blocking of 857 websites, the government on Tuesday reviewed its order and decided to lift ban and allow websites which do not carry child pornography material but ISPs refused to follow the government's directive and said on Wednesday that the directive was “vague and unimplementable”.

Internet Service Providers Association of India (ISPAI) said, "ISPs have no mechanism to filter out child pornography from URLs, and the further unlimited sub-links".

Earlier in July, the government has assured the Supreme Court that all possible measures would be taken to block porn sites, specially those deals with child pornography.

Government has launched crackdown on more than 800 pornographic websites prompted nationwide debate about censorship and freedom.

DoT said the aim was to prevent pornography becoming a social terror.

Explaining the rationale behind the original directive, Prasad said, "The instant action is basically in obedience to the observation of the Supreme Court where the court asked the department to take action on the list of alleged porn sites provided by the petitioner.

Government will have to take a fresh look into the matter after next petition on August 10.