NEW YORK (CNNMoney) -- The FBI is investigating hacking attacks on multiple American banks, including one against JPMorgan Chase that caused a data breach, according to a U.S. official familiar with the probe.
The official told CNN the extent of the damage from the JPMorgan attack and where it came from have not yet been determined.
A JPMorgan spokesperson said the bank has not detected "unusual" fraud activity at this time but is working with law enforcement to determine the scope of the apparent breach.
"Companies of our size unfortunately experience cyberattacks nearly every day. We have multiple layers of defense to counteract any threats and constantly monitor fraud levels," the JPMorgan spokesperson said.
The FBI said it launched a broad investigation into recent attacks.
"We are working with the United States Secret Service to determine the scope of recently reported cyber attacks against several American financial institutions," the agency said in a statement.
Hackers from Russia and eastern Europe are often top FBI suspects in cyberattacks. The timing has raised suspicions given the mounting tensions between Russia and the West over Ukraine and economic sanctions.
JPMorgan said it invests heavily in cyber security. A letter to shareholders earlier this year said the bank plans to spend more than $250 million a year and deploy over 1,000 people to focus on cyber security by the end of 2014.
JPMorgan directed customers who detect suspicious activity on their accounts to contact the bank.
CNN International's Saskya Vandoorne contributed to this report.
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