The government knew Northern rail passengers would face major disruption two years ago, an MP has claimed.
Wigan MP Lisa Nandy said she had been handed Department for Transport emails in which officials discuss "propagating myths" to divert attention from route closures.
Speaking during Prime Minister's Questions, she said the emails were a "disgrace".
In response, Theresa May said she would not comment on "leaked" documents
Responding to Ms Nandy's allegations, the Prime Minister said a panel was set up to advise the Department for Transport about the plans.
Ms Nandy said in the emails "officials describe key Northern routes as valueless, discuss classic handling strategies for members of parliament, discuss whether to throw a sop to Northern passenger groups and debate whether to propagate myths in order to divert public attention from agreed planned route closures."
She asked why the government had "withheld this key information" from the house and the public.
Ms Nandy also tweeted some examples of the correspondence involving the line between Wigan and Southport.
A new timetable was introduced on 20 May and Northern passengers have faced widespread disruption and cancellations.
The DfT has been asked to comment.