The Thrift Savings Plan has warned its participants against using a free iPhone app being offered through the Apple store, saying it is not an official offering of the 401(k)-style program for federal employees.

The app, called TSP Funds, asks account holders for their account login information, but providing that information “could result in a security risk to your account,” the TSP said.

The TSP’s own access portal requires users to enter account identification and a password. It also provides information about steps investors should take to protect their accounts.

The TSP last year disclosed that a 2011 hacking incident had been discovered in which Social Security numbers and other personal information on more than 120,000 account holders were compromised.