More Americans are concerned about the security of online shopping, according to a new study conducted by Lieberman Research Group and sponsored by Unisys Corp., a security consultant.

In the telephone survey of 1,008 adults in February, 51% said they were seriously concerned about the security of online shopping and online banking, compared with 37% in a similar survey during the second half of 2010. Unisys says the 51% result is the highest expression of concern since the survey launched in the second half of 2007. The survey did not specifically analyze why the jump occurred.

“The growth of smartphones and tablet PCs appears to have helped fuel awareness of security concerns among the general public,” says Patricia Titus, vice president of Unisys. “But ironically, previous iterations of the survey have shown many of these users don’t appreciate the lack of security these mobile devices have compared with their desktop and laptop computers.”

Unisys says that Internet users should secure their mobile devices. “We’ve found that most smartphone users don’t protect their devices with passwords,” Titus says. “There’s a false sense of security that consumers can perform the same transaction on their mobile devices than they could on a PC, which might have a full-blown security software package loaded on it.”

The study also found 70% of Americans are seriously concerned about identity theft and 68% are seriously concerned about having their credit or debit card details stolen.