(Adds new data on cenbank reserves)
By Jorge Otaola and Walter Bianchi
BUENOS AIRES, April 28 (Reuters) - Argentina's central bank bought $630 million of dollars on the local currency market on Tuesday in one of its largest-ever purchases, a source told Reuters, bolstering the country's precariously low hard currency reserves.
Some $500 million of the dollars purchased were proceeds from last week's $1.5 billion auction of bonds by state energy company YPF, the source added.
Reserves closed at $33.216 billion on Tuesday, their highest level since Nov. 4, 2013 but still low given the need to finance an energy deficit and high debt servicing costs this year.
Largely shut out of global credit markets since a massive debt default in 2002, Argentina imposed currency controls three years ago to stem a hemorrhaging of hard currency and the depletion of its reserves.
Since then, all dollars flowing into Latin America's third-largest economy have had to pass through the central bank, which closely regulates the currency market, restricting how much importers and savers may buy.
Those restrictions have hampered imports and fueled a rampant black market as Argentines look for channels to buy dollars to shield their savings against inflation.
Yet the restrictions have proven insufficient to protect the reserves, which fell last year and set the country on track to a balance of payments crisis.
The government has set about taking unorthodox measures, such as currency swaps with China, to tide it over until the end of its term. Presidential elections are set for October and President Cristina Fernandez cannot run for a third term.
The proceeds from Argentina's $1.4 billion bond sale last week also helped bolster reserves.
Markets widely expect Argentina's next government to implement a more sustainable solution to its financing problems by resolving its long-standing battle with investors over unpaid debt in order to be able to reaccess international credit markets. They also see it lifting currency restrictions. (Reporting by Jorge Otaola and Walter Bianchi; Writing by Sarah Marsh; Editing by Jeffrey Benkoe, Ted Botha and Cynthia Osterman)