Reports of thefts on the London Underground have risen by 80% over the last three years, according to recent figures.
The figures showed there were 6,825 reports of theft of personal property in 2018-19, compared 3,730 in the 2016-17 period.
The figures obtained by BBC London from British Transport Police (BTP) showed that the Piccadilly and Central lines saw the highest number of reports with 1,125 made in the past year.
The BTP admitted they did not know exactly what had caused the steep rise.
A spokesman said: “Tackling all forms of crime on the London Underground network is a top priority and we are committed to reducing theft and pickpocketing.”
He said the tube network had grown significantly over the years, with nearly 5 million journeys being made every single day.
“While theft has risen, it still remains incredibly rare for a passenger to become a victim of theft when using London’s transport network,” he said.
“Nevertheless, we have teams who are focussed on investigating theft and proactively patrolling the Underground looking for pickpockets and other criminals. They are successful in identifying those who are out to commit crime, and securing custodial sentences.”
He added that passengers can help us tackle theft by “being vigilant and keeping valuables secure and away from opportunistic thieves”.
BTP also pointed out that a large portion of the theft stats provided to the BBC would be for lost luggage. For example, if someone leaves their phone or bag on a train and it doesn’t turn up at lost property. Not all the figures are pickpocketing crimes.
Siwan Hayward, director of compliance, policing and on-street operations for Transport for London (Tfl) stressed that London’s transport network is “a safe, low crime environment”.
Tfl fund thousands of officers dedicated to policing its transport network. Around eleven million passengers travel on TfL’s public transport services each day with very few of them ever experiencing or witnessing crime, he said.
“We have seen an increase in theft offences which is largely a result of organised criminal networks operating in London targeting public transport and other busy places.
“We are working with the police to target thieves which includes targeted uniform and plain clothes police patrols to disrupt their activity, as well as providing crime prevention advice to our customers.”