NSW premier condemns station sex assault

NSW Premier Barry O'Farrell says the alleged sexual assault of a 17-year-old girl at a Sydney train station is a terrible tragedy but "regrettably, crime happens".

A 34-year-old man has been charged after he allegedly forced the girl off a train and into toilets at Strathfield Station and assaulted her on Wednesday.

Speaking to reporters at Tamworth on Friday, Mr O'Farrell said his government was assisting police but could never eliminate crime altogether.

"I've never been aware of any premier, any prime minister, any chief minister who will say there'll never be another serious crime that occurs on their watch" he said.

"But we have increased police, we've given police increased powers and we've now got police patrolling public transport.

"No one can guarantee crime will never occur. What we can do, though, is ... take steps to ensure it's prevented."