The U.S. may begin issuing 50-year ultra-long government bonds for the first time, the Treasury Department said Wednesday.

The department is "exploring" potential additions to the current suite of Treasury securities, including a 20-year nominal coupon bond, a 50-year nominal coupon bond and a one-year floating-rate note linked to the Secured Overnight Financing Rate, according to the Treasury's quarterly refunding statement released Wednesday.

"Treasury is taking a proactive approach to prepare for prospective future financing needs," the statement said. No timeline was given for the issuance.