Metro Vancouver's Transit Police are warning riders about a spike in robberies involving smartphones, after a 31 per cent increase in the violent theft of electronics.

While nearly all types of crime are on the decline in Canada, Vancouver police also report seeing a 20 per cent increase in violent robberies of electronics in the past year.

To warn passengers about smartphone thefts on transit, police have compiled a video showing footage of several different incidents involving the theft of electronic devices.

One example shows a suspect lurking by the door of a subway train as he watches a woman using her phone.

As the train doors are just about to close, the suspect apparently grabs the phone from the woman and dashes off.

RCMP Insp. Tim Shields said smartphone theft has become a lucrative crime, because they're easy to resell and hard for police to trace.

"They are so easy for the thieves to resell within 24 hours on Craigslist, that it's almost the equivalent of cash," said Shields.

That's expected to change in September, when the cellphone industry launches a nationwide database to blacklist stolen phones.

In Australia, a similar system cut cellphone theft by a quarter.

"We're hopeful that the success we've seen in Australia will be reflected here in Canada," said Shields.

Transit police spokesperson Anne Drennan said the best thing people can do is keep an eye on what is going on around them.

"You absolutely have to be aware of your surroundings, particularly when you are using an electronic device," said Drennan.

Police also recommend turning on the password protection on your phone and downloading an app that allows you to trace your phone.