A survey found 55% of passengers felt safe in stations this year, an improvement of only one per cent since 2002.

Most respondents blamed anti-social behaviour by other passengers, but half said lack of station staff made them concerned for their safety.

The NAO report on the state of Britain's railway stations - which was undertaken before last month's bomb attacks in London - found passengers were most unhappy with 2,000 smaller stations that had part-time or no staff.

Passengers were reasonably satisfied with the 95 largest stations, and were most happy with help offered by staff and passenger information.

But satisfaction was lowest for facilities, station environment, personal security and car parking.

Efforts to improve security through the Home Office-sponsored Secure Stations Scheme had made limited impact, according to the report. Fewer than 5% of stations were accredited, and many of those never had high levels of crime.

However, a Safer Parking Award had brought sharp falls in crime after better lighting, CCTV and security was introduced at stations seeking accreditation.

The NAO said hopes at privatisation that train operating companies would improve stations they ran had not been fulfilled, but that could change with stricter requirements written into franchises.

It warned that more private money was needed to raise stations to the standards expected by passengers but there was no system for attracting that investment, although there were plans to use the private finance initiative.

Network Rail also needed to be put under more pressure to improve stations' environment by the Office of Rail Regulation.

The report called for more train operators to take part in the Secure Stations and Safer Parking Award schemes, for passengers to be more involved with monitoring TOCs performance at their stations, and for a star rating system to be introduced judging stations against minimum requirements.

Network Rail chief executive John Armitt said they were already consulting on ways to simplify procedures for improvements to stations proposed by the private sector. It was also inviting developers, investors, and property owners to bid for improvement projects.