The Panama Papers leaker has gone public, singling out New Zealand Prime Minister John Key.

Calling themself "John Doe", the person behind the biggest leak or hack of all time has released an 1800 word statement.

They refer to "issues that need fixing", and say: "Prime Minister John Key of New Zealand has been curiously quiet about his country's role in enabling the financial fraud Mecca that is the Cook Islands."

The statement refers to just one international leader - Mr Key.

It does not include any details of direct personal involvement by Mr Key.

Titled "The Revolution Will Be Digitized" the statement gives justification for the leak, saying that "income inequality is one of the defining issues of our time" and says that government authorities need to do more to address it.

The leak is mostly believed to be a hack.

"John Doe" says that there is no link with any international spy agency and offers to cooperate with the relevant authorities.

The statement was issued to the German newspaper Süddeutsche Zeitung and the International Consortium of Investigative Journalists -- and the source's identity has been verified by them.

The Panama Papers are due to be released in a searchable database on Tuesday at 6am.

Newshub.