Police are dealing with a significant increase in the number of violent and sex crimes on the London Underground and DLR network, according to newly-released figures.British Transport Police statistics obtained by the Evening Standard show 1,961 violent sex crimes were recorded across the network in the first six months of this year - a rise of 41% from the same six-month period in 2015.Of the 1,961 crimes reported, 460 were sex crimes, a rise of 40% from the same period in 2015, when there were 328 sex crimes reported across the network.The increase comes as London Underground prepares to roll out its long-awaited Night Tube service on certain lines from next weekend, but a senior British Transport Police official said the figures should be measured against the ever-growing popularity of the network."It is disappointing see that after 11 years of reductions in crime that there was an increase last year," Chief Superintendent Martin Fry told the Evening Standard . "However, this must be seen in the context that during 2015/16, passenger journeys increased by more than two million, bringing the total number of passenger journeys up to more than 11 million per day.""In 2005/2006, there were more than 18 crimes per million customer journeys in 2005/6 and that is now down to just 7.3 – meaning the chances of becoming a victim of crime on London’s rail network are extremely low," he added. "This does not mean we are complacent, each crime is one crime too many."Though the figures show that certain London Underground lines are comparatively safer than others, it goes without saying that we all should all be vigilant when travelling on any part of the network, from Zone 1 to Zone 9. To report a crime or incident, call the British Transport Police on 0800 40 50 40, or send a text to 61016. In an emergency, always call 999.Last year, the British Transport Police launched the "report it to stop it" campaign to tackle unwanted sexual behaviour on London's public transport. Find out more about the campaign on its Tumblr