Lost smartphones are likely to be mined for valuable information by strangers who find them, according to the results of a sting operation conducted by computer security firm Symantec.

Symantec intentionally "lost" 50 smartphones at shopping centers, bus stops and other public places in cities in the United States and Canada and then monitored activity on devices by using embedded software.

The feedback showed "a very high likelihood of attempts to access both sensitive personal and business-related information will be made if a lost and unprotected smartphone is found by a stranger."

The results of "Smartphone Honey Stick Project" released Monday also showed that owners of lost smartphones shouldn't count on finders to try to contact them.

Half of the people who found the smartphones reached out to return them to owners, but applications promising to hold personal information including online banking were accessed in 89 percent of the cases, according to Symantec.

Work-related files with labels such as "human resources cases" were dipped into on 83 percent of the found phones. Overall, personal or business files were tapped into on 96 percent of the smartphones.

Symantec advised smartphone owners to lock screens with tough passwords and keep handsets close while out and about.