Ministers are facing accusations they "cynically" hid delays to major rail improvement programmes from voters during the general election campaign.
Labour said documents obtained through the Freedom of Information Act (FoI) made clear ministers were aware as early as last March that "deferrals" to improvement schemes would be required in the weeks following the election.
The disclosure comes after Transport Secretary Patrick McLoughlin sparked a political storm last month when he announced the electrification of the Trans-Pennine and Midlands mainline routes was being "paused" despite the Tories having campaigned on a pledge to create a "northern powerhouse".
The Department for Transport (DfT) insisted that Mr McLoughlin had always been open with MPs about the "emerging issues" surrounding the electrification programme in the run-up to the general election.
However, shadow transport secretary Michael Dugher said that Network Rail board minutes from March 19, released under FoI, indicated minsters were already aware that decisions would be required once the election in May was out of the way.
The minutes state that Network Rail strategy director Paul Plummer was due to meet the DfT and the Office of the Rail Regulator, noting: "Decisions were due to be made regarding various key enhancement projects from June".
The minutes then go on to refer to: "The decisions required jointly with the DfT re enhancement deferrals from June."
Mr Dugher said the documents showed that ministers must have known before the election that vital rail electrification projects would have to be shelved.
"It is becoming increasingly apparent ministers deliberately decided to cynically mislead people during the general election campaign that key rail lines would be electrified in the Midlands and the North, knowing full well that they would then renege on these commitments after the election," he said.
A DfT spokesman insisted however that Mr McLoughlin had always been clear about the problems facing the electrification programme since before the general election.
"The Secretary of State has been open with Parliament about the emerging issues on electrification, discussing these issues with the Transport Select Committee on December 15 and again on March 9. On March 9 he specifically acknowledged that the 2019 completion date for North Trans Pennine electrification would not be met," the spokesman said.
"While in late March Network Rail flagged emerging costs, these were subject to further review. DfT officials were clear that a fuller assessment of the whole programme was needed before any decisions could be taken.
"In June, following this fuller assessment, the Secretary of State was advised that forecast costs had increased significantly and that Network Rail was no longer confident that the whole programme could be fully delivered within Control Period 5 (2014-2019)."