Teacher unions have told schools to refuse requests for their national standards data.
The New Zealand Educational Institute has told boards of trustees and principals not to give information about their national standards results to the media and to refer any requests for such information back to the Ministry of Education.
The Dominion Post has sent Official Information Act requests to all schools in the Wellington region asking for national standards information they sent to the Ministry of Education showing how many pupils are meeting national standards in reading, writing and maths.
About 10 schools replied.
Institute president Ian Leckie said the request is an inevitable but regrettable outcome of the National Standards process.
"We are entering a new era of 'naming and shaming' schools to sell newspapers and, even worse, the publication of league tables will be unfair and based on faulty, misleading and valueless information," he said.
Data on achievement standards of New Zealand's primary school children has been collected by the ministry for the first time.
"National standards do not give parents good quality information about their child's progress," said Mr Leckie.
He said the news media should look at its own ethics before publishing the data.
Principals Federation president Paul Drummond advised schools to withhold information from the media - but suggested schools could provide general information.
"The Ministry of Education has indicated its intention to release information later in the year so we would question why it has advised the news media to seek this directly from schools. Especially when the ministry is not in a position to give any kind of accurate evaluation based on this information.
Education Minister Hekia Parata has said the Ministry will look at ways to publish data but was not in favour of the media releasing league tables.