The U.S. Embassy in Guatemala is advising U.S. travelers to Guatemala to stop using their ATM cards in Antigua. Reportedly, criminals are using cloned numbers to withdraw funds from unsuspecting travelers. Please read the entire alert here, dated January 27, 2011. Below is an excerpt:

Dear American Citizen:

The following is a Warden Message concerning ATMs information. Please share the following information with any other Americans you know, as soon as possible. It should be disseminated as widely as possible within the American citizen community.

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Over the past few weeks there have been numerous reports of criminals in Antigua using cloned Automatic Teller Machine cards to withdraw money from the bank accounts of unsuspecting travelers. Customers using ATMs have lost thousands of dollars — often the entire balance of their ATM bank accounts. All ATMs can be subject to these attacks. We are working with the Guatemalan authorities to solve this serious problem. In the meantime, the U.S. Embassy advises against the use of ATMs in Antigua, if at all possible. As an alternative, citizens can withdraw money using a major credit card at banks that deal in foreign exchange or at foreign exchange offices. U.S.citizens with a Guatemalan bank account can also cash checks at their local bank.

ATMs located inside a bank may offer a greater degree of security. For those staying in hotels, hotel management might be willing to provide cash and charge the foreign exchange transaction to the room bill. 

I learned of this alert on a Guatemalan listserve to which I belong, posted by Caroline Tiffin.