Network Rail has been fined £1 million after it breached health and safety laws at a level crossing where two teenage girls were killed.

Olivia Bazlinton, 14, and Charlotte Thompson, 13, were hit by a train in 2005 as they crossed the tracks at Elsenham station footpath crossing in Essex. Judge David Turner QC, sentencing at Chelmsford Crown Court, fined the authority responsible for the UK's railway network £1 million and ordered it to pay £60,000 costs.

Olivia and Charlotte were killed on December 3 2005 as they crossed a footpath leading to Elsenham station platform. The crossing was fitted with warning lights and yodel alarms.

A London-to-Cambridge train passed over the crossing with the red lights and yodel sounding - a warning for foot passengers not to cross.

After the train passed, the lights remained on and the alarms continued to sound as another train, travelling from Birmingham to Stansted Airport in Essex, was going to pass through the station. The girls opened the unlocked wicket gates and walked on to the crossing. They were both struck by the Stansted train and killed.

Last November, the Office of Rail Regulation (ORR) announced that it would prosecute Network Rail over those deaths after reopening its investigation into the accident.

The move came after the Transport Salaried Staffs Association joined the girls' families in demanding a public inquiry amid claims that two safety documents were not disclosed to the Essex coroner at the 2007 inquest into the deaths.

At a hearing in January, Network Rail pleaded guilty to three health and safety breaches. The authority admitted failing to carry out a sufficient risk assessment, failing to properly control protective measures at the level crossing, and failing to prevent the girls from being exposed to the risks which led to their deaths.

Network Rail chief executive Sir David Higgins said: "On behalf of Network Rail I apologise for the mistakes made by us in this tragic case that contributed to the deaths of Olivia and Charlotte. Nothing we can say or do will lessen the pain felt by Olivia and Charlotte's families but I have promised the families that we will make level crossings safer, and we will deliver on that promise.

"Fundamental changes to the way we manage and look after the country's 6,500 level crossings have, and are being made. In recent years we have reassessed all of our crossings and closed over 500. There is still much to do and we are committed to doing what is necessary to improve our level crossings."