US telecom giant AT&T said Monday it was advising customers of an apparent hacking attempt but that no accounts were breached.
"We recently detected what could have been an organized attempt to obtain information on a number of customer accounts," an AT&T spokesman told AFP by email.
The hackers attempted to determine whether AT&T telephone numbers were linked to online AT&T accounts, the spokesman said.
"No accounts were breached and our investigation is ongoing to determine the source or intent of the attempt to gather this information," he said.
"In the meantime, out of an abundance of caution, we are advising the account holders involved," the spokesman added.
In June, a 26-year-old San Francisco man pleaded guilty to writing code used to steal email addresses and personal information belonging to 120,000 Apple iPad subscribers from AT&T computer servers.
AT&T shares were down 1.29 percent at $28.27 in early afternoon trading on Wall Street on Monday.
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