By Peter Woodman, Press Association Transport Correspondent
Rail regulators expressed "frustration" today at the slowness of safety improvements by infrastructure firm Network Rail (NR).
The company made good progress in some areas during the last year but also suffered "setbacks and failures", the Office of Rail Regulation (ORR) said.
NR missed many of its annual targets for 2010/11, including some for delays and punctuality, the ORR said.
It added that NR would have to submit plans to show how it would better cope with the delays and with winter weather conditions.
NR faced "big challenges ahead" if it was to meet future performance targets, the ORR concluded.
The ORR said: "Weaknesses in NR's safety culture have been recognised, including the exposure of flawed injury (to staff) reporting.
"ORR is often frustrated by the slow pace of necessary safety improvements, and a number of enforcement notices followed failure to make timely progress."
The ORR added that it was "concerned" at the "recent upward trend in delays".
ORR chief executive Bill Emery said: "NR made good progress in some important areas last year - delivering improvements to many railway stations and lines across the country.
"However, we have also seen performance setbacks and failures which mean that NR faces big challenges if it is to meet the increasingly demanding targets it is funded to achieve."
Mr Emery went on: "NR missed the majority of its operational performance objectives for areas like punctuality, and it quickly needs to take steps to improve its safety culture. We want to see NR learn quickly from its problems and to focus on improving performance that matters most to passengers.
"With targets getting increasingly tough year on year, ORR is pressing NR not to fall off the pace of all its regulatory commitments - and to act now."
Bob Crow, general secretary of the RMT transport union, said: "If you are serious about improving safety and operational standards at NR then the last thing you need is cuts to safety-critical jobs and the fragmentation of a new round of privatisation which is the very thrust of the (Sir Roy) McNulty rail review.
"With this ORR report homing in on safety it is a warning shot to all those demanding a further round of cuts and privatisation at NR that would drag us back to the days of (NR predecessor company) Railtrack and raise again the spectre of the Hatfield and Potters Bar (accidents) over Britain's railways."