The majority of online banking customers reuse their login credentials to access non-financial and much less secure websites, a recent study has revealed.

The survey, conducted by online security services company Trusteer, has found that 73 percent of bank customers use their online account password to access other websites, and that 47 percent use both their online banking user ID and password to login elsewhere on the internet.

The findings were based on a sample of over 4 million users of the Rapport browser security service, many of whom are customers of leading North American and European banks.

According to the survey, this widespread reuse of online banking credentials is being exploited by criminals who have devised various methods to harvest login credentials from less secure sources, such as webmail and social network websites. Once acquired, these usernames and passwords are tested on financial services sites to commit fraud.

The research has also revealed that when a bank allows users to choose their own user ID, 65 percent of users share this ID with nonfinancial websites. Also, when a bank chooses the user ID for its customers, 42 percent of customers use the bank issued user ID with at least one other website.