Jerusalem (CNN) -- The websites of the Tel Aviv Stock Exchange and of El Al, the Israeli airline, were brought down Monday morning by an apparent hacking attack.

CNN: Hackers attack two Israeli websites

In addition to exposing Israel's credit-card holders, hackers from outside the country are believed to be responsible for temporarily slowing down the websites of the Tel Aviv stock exchange and El Al Israel Airlines Ltd. in January.

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Idit Yaaron, the spokeswoman for the Tel Aviv Stock Exchange, told CNN that the main site of the stock exchange where the trading takes place was not harmed and operates on a very high level of Internet security.

CNN: Hackers attack two Israeli websites