When a French utility completed its sale of 100-year bonds denominated in pounds in January, Mexico took note.

Four years after becoming just the second country to sell dollar debt due in 100 years, Mexico last week issued 1 billion pounds (US$1.66 billion) of securities that mature in 2114, becoming the only nation with two century bonds. U.K. investors accounted for 84 percent of buyers in the March 12 offering, said Alejandro Diaz de Leon, Mexico's public debt chief. The sale by Electricite de France SA in January underscored the pent-up demand for longer-dated debt in pounds, according to Barclays Plc, which helped underwrite both deals.

"Mexico historically has distinguished themselves from other sovereigns in terms of always looking at creative ways of getting more efficiency in terms of their debt management strategy," Raul Martinez-Ostos, head of Mexican operations at Barclays, said by phone from Mexico City. "Here it was really driven by real-money institutional accounts in the U.K."