MINNEAPOLIS (WCCO) – State commerce officials say a statewide sweep of gas stations last month found nine hidden credit card skimmers, which criminals use to steal credit and debit card information from unsuspecting customers.

Mike Rothman, the Minnesota Commerce Commissioner, announced on Thursday that the inspection was conducted over a three-week period, examining readers at more than 1,000 gas stations in the Twin Cities metro and Greater Minnesota.

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“The Commerce Department is cracking down on these skimmers to protect Minnesota consumers against identity theft and fraud,” Rothman said in a statement. “We are working to make sure the state’s gas pumps are secure and customers’ credit and debit card information is safe.”

The recent inspection checked 8,500 credit card readers. There are about 52,000 such readers in the state.

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Moving forward, the Commerce Department says its inspectors will be looking for skimmers or any sort of tampering with gas pumps as part of their routine.

Officials say they are also working with gas stations to train their operators on how to protect against skimmers.

Consumers are advised to inspect card readers at gas stations before swiping a card. If one sees signs of forced entry or tampering, the gas station clerk should be alerted.

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To avoid skimmers, it’s advised that consumers pay inside the gas station or with cash. To protect against fraud, one should be sure to monitor bank and credit card accounts.