Attorney-General Christian Porter says social media platforms should be treated the same as traditional publishers under defamation law, a change that would present a fundamental new challenge for global companies such as Facebook and Twitter.

Mr Porter made the declaration in a speech on Wednesday, also backing a suite of reforms to defamation laws which he said "don't strike the perfect balance between public interest journalism and protecting individuals from reputational harm". The changes are being advanced under a nationwide review of defamation law.

Mr Porter described current laws as unfair for traditional media outlets, a position which will be welcomed by media companies pushing for change under the "Your Right to Know" campaign. Defamation reforms are one of six key proposals being pushed by the media outlets, who have sounded the alarm about threats to journalism in Australia.

As part of the review being jointly undertaken by federal and state governments, led by NSW, Mr Porter said updated laws were necessary.