An inquiry into the deaths of two girls at an Essex level crossing more than five years ago has been reopened after the discovery of new evidence.
Olivia Bazlinton, 14, and Charlotte Thompson, 13, died when a train hit them at Elsenham in December 2005.
An unseen Network Rail risk report, which was written in 2002, considered locking the gates to the pedestrian crossing as trains approached.
The Office of Rail Regulation (ORR) is reviewing the document.
Inspectors will look at whether it affects the outcome of their previously concluded investigation.
On Saturday Olivia's father Chris Bazlinton, 62, said the document was not released for the 2007 inquest by Network Rail and that amounted to "a cover-up".
Olivia and Charlotte were killed by an express train at Elsenham railway station on their way to Cambridge for a shopping trip.
The inquest jury returned a verdict of accidental death.
"The Office of Rail Regulation confirms it has recently received a copy of a key document which it had not seen previously, relating to the tragic double fatality at Elsenham level crossing in December 2005," said an ORR spokesman.
"Press reports over the past few days have correctly reported that the record of a risk assessment undertaken in 2002 was not included in a bundle of documents provided to meet the inspector's request immediately after the accident."
A statement from Network Rail said: "The deaths of Olivia Bazlinton and Charlotte Thompson over five years ago, were a tragedy.
"It was also an accident, as the coroner's verdict clearly stated. The thoughts of Network Rail remain with the girls' families and friends.
"Every accidental death at a level crossing is tragic. Fortunately they are rare and Britain has a safety record that stands up well to international comparisons.
"Just this week Network Rail unveiled more measures to deter incidents at level crossings.
"Our awareness campaign began over six years ago and was commended by the coroner at Olivia and Charlotte's inquest."