Transport for the North, which was set up by the government this year to oversee the region's railways and roads, has refused a Freedom of Information (FOI) request to disclose correspondence between themselves and Northern about a new timetable, which was blamed for the havoc.
The botched implementation of the timetable, on May 20, caused weeks of misery for commuters, with Northern cancelling up to 310 trains a day at one point.
Bosses have consistently blamed the delays and cancellations on the narrow timeframe Northern had to plan for the changes.
But Transport for the North (TfN) claimed in July they had no prior warning there may be issues, with director David Hoggarth saying, "it was only on May 20 we realised we had a problem".
Now it has said that a request to publish communication between themselves and Northern between March 1 and June 30 about the issue is "unreasonable".
Its response to the FOI request said: "It would cause TfN a disproportionate burden in complying with the request and involve a diversion of resources."
While acknowledging there would be a public interest in revealing the information, TfN said reasons not to divulge it included, "protecting public authorities from exposure to disproportionate burden or disruption in handling information requests."
It added: "Dealing with manifestly unreasonable requests can place a strain on resources and get in the way of public authorities delivering services."
It concluded that this outweighed the public interest in publishing any information.
TfN were contacted for further comment, but declined.