Image caption On the tracks: Jenny Agutter as Bobbie, Sally Thomsett as Phyllis and Gary Warren as Peter

Forty-two years after it was released, classic family film The Railway Children has prompted its first complaint to the British Board of Film Classification.

"The correspondent was concerned that children may be encouraged to play on railway tracks as a result of seeing the film," the BBFC's annual report reveals.

The tear-jerking drama, directed by Lionel Jeffries, starred Bernard Cribbins, Dinah Sheridan, Jenny Agutter and Sally Thomsett.

The report, published on Thursday, said the BBFC judged that it was "very unlikely" that The Railway Children would promote "such dangerous activity".

"The Railway Children is set in the Edwardian period and trains and access to railway property are very different today," the censor said.

"The film also demonstrates the potential harm to children if proper care is not taken."

Based on the E Nesbit novel, it was filmed on the Keighley and Worth Valley Railway and chronicles the adventures of three children forced to move from London to Yorkshire when their father is imprisoned after being falsely accused of selling state secrets.

Senior examiner Craig Lapper said the film had always been rated U - meaning suitable for all - but that the BBFC website now drew attention to the fact that the "playing on railway lines was in an archaic context".

'Dark and unsettling'

Hammer chiller The Woman in Black, starring Daniel Radcliffe, generated the most public feedback to the censor in 2012.

A total of 134 cinema-goers complained to the BBFC that the film was "too dark and unsettling" for a 12A certificate.

The film generated £21m in UK cinemas in 2012, making it the second most popular British film of 2012 after Skyfall.

The Hunger Games, in which children and teenagers are forced to fight to the death on TV, generated 43 complaints about its violence and theme.

The BBFC had classified the film 12A following edits to remove some violent detail.

There were a "small number of complaints" criticising the decision to cut the film.

The BBFC said: "These were mostly from young fans of the books who believed the film should remain intact and that any cuts to the violence would sanitise its impact."

Men in Black 3 received 50 complaints for its language, violence, horror and sexual innuendo. The film was classified PG, as were the earlier two films in the franchise.

In 2013, the most complaints have been about the violence in 12A-rated Tom Cruise action movie Jack Reacher.

In 2012, the BBFC classified 850 films - the highest number since 1965. No film or video works were refused a classification.

Other trends in 2012 included a 40% rise in the number of classifications of online-only material.

BBFC director David Cooke said that while the internet downloads did not fall under BBFC's remit - but could be submitted voluntarily - it was "becoming clearer that both politicians and the public want us to play a role".

The BBFC also backed government plans to change the rules on videos that are exempt from classification - such as music videos, documentaries and extreme fighting videos.

"It's become apparent that some of those exemptions have enabled some very strong material," Mr Cooke said.