A rail union has raised safety concerns on the 15th anniversary of a train crash in which four passengers died.
A GNER InterCity 225 train bound for Leeds from London King's Cross derailed south of Hatfield station on this day in the year 2000. Four passengers died in the accident and a further 70 were injured.
The Rail, Maritime and Transport union claimed that a new infrastructure maintenance system had created "confusion."
General secretary Mick Cash said: "Network Rail needs to take this message seriously otherwise RMT will have to resort to industrial action to get the current dangerous programme halted."
Mick Whelan, general secretary of the train drivers' union Aslef, said: "As an industry we should never forget those who died, and all those whose lives were changed, because of the Hatfield rail crash. And, as an industry, we should never forget the lessons that we learned in what is, and always will be, a safety-critical industry.
"Hatfield exposed the serious shortcomings of the privatised infrastructure company Railtrack. The subsequent inquiry revealed that the company - which put profit before safety - had failed in its duty of care to passengers and workers.
"As some people talk about privatising Network Rail we should reflect on what that means and where it goes. Private companies put profit - and their dividends to shareholders - before safety and take short cuts which result in accidents, injuries and deaths."