A potential "major rail tragedy" was avoided last week by workers who spotted a massive gap in tracks on the high-speed East Coast Main Line, the RMT revealed today.
The rail union said the six-inch section in the track could have derailed trains carrying hundreds of passengers.
But quick-thinking rail workers spotted the gap near Selby in Yorkshire last Friday and that part of the track has since been replaced.
Worryingly this discovery comes just two weeks after staff spotted a similar break just a few miles away.
RMT general secretary Bob Crow labelled the discoveries "damning evidence" that reveal rail operators are cutting costs to boost profits despite the "potentially lethal consequences."
He warned that Britain could witness another Hatfield rail disaster if the government does not reverse cuts it promised to make in a 2011 review of rail services.
"Staffing, inspections and track renewals have been cut in the dash to save money and there is massive pressure right from the top of government to keep services running at all costs regardless of the potential human cost," Mr Crow said.
"If we don't reverse the cuts on Britain's railways another major tragedy is inevitable."
Four people died in the Hatfield tragedy which exposed massive failings in track maintenance carried out by private firm Balfour Beatty who were subsequenty fined £10 million.
Campaigning by the union has forced the Rail Accident Investigation Branch (RAIB) to investigate last week's incident.
And today RAIB told the Star it is just one of a number of track maintenance issues it has been investigating since September 2012.
As a result of the recent discoveries, the rail union is calling on operators to end their practice of sub-contracting track maintenance and bring the work back in house.
Mr Crow said: "The current contractor staff should be transferred over to direct Network Rail employment.
"We also want the pressure from the centre to run services at any costs lifted to enable safety-critical works to take place immediately."