(Adds details on first long bond, context)
TORONTO, July 9 (Reuters) - Canada is considering issuing more ultra-long bonds, maturing in 50 years, which would allow the government to lock in borrowing costs near historic lows through an expansion of an offering first made earlier this year.
The Department of Finance said on Wednesday the issue would be done through reopening the 2.75 percent government of Canada bond maturing Dec. 1, 2064, using a syndicated process, subject to favorable market conditions.
Issuing bonds at a low cost with such a long duration would contribute to a reduction in refinancing risk, the government said.
Canada is one of the few leading industrialized nations with an undisputed AAA rating and its bonds are in high demand.
When the bond was originally made available in late April in an issue worth C$1.5 billion, it was the first time Canada had issued a 50-year bond. Sovereign bonds with a 50-year duration are not as common as 30-year bonds, although several Canadian provinces already issue ultra-long bonds. (Reporting by Leah Schnurr; Editing by James Dalgleish; and Peter Galloway)