The personal information of roughly 123,000 federal employees -- including at least 25 members of Congress -- may have been exposed after a cyber attack last year on the Thrift Savings Plan (TSP), FOX News Channel confirmed Friday.

The retirement savings plan is available to almost all current and retired employees in every branch of the government, including civilian and military personnel of the Department of Defense. Its assets total $313 billion, FOX reported.

The cyber attack occurred last July against a TSP contractor, Serco Inc. The FBI notified both Serco and the TSP last month about the attack.

"There is no evidence of any funds being diverted or identity theft resulting from the incident," Serco said in a statement released Friday. "An extensive forensic analysis of the data also shows no indication that the TSP network, which supports TSP's 4.5 million participants, was subjected to unauthorized access."

According to Serco, the names, addresses and Social Security numbers of roughly 43,000 individuals were potentially compromised in the incident. The Social Security numbers of an additional 80,000 individuals may have been exposed without additional identifying information.

"Serco regrets this incident and the inconvenience it may cause to some Thrift Savings Plan participants and payees whose personal data was involved," said Serco Chairman and CEO Ed Casey in the statement. "We have fortified our information security measures and cyber defenses."

Those affected by the cyber attack will receive notification letters and services such as fraud consultation and credit counseling.