Argentina's GDP grew 1.9 percent in 2012, a sharp slowdown from the 8.9 percent expansion the previous year, according to figures released Friday.
The country's national statistics institute, whose data has been questioned by the International Monetary Fund and others, also reported that December 2012 economic activity grew 1.1 percent compared to the same period in 2011.
Last year's drop came after a period of strong growth that began in 2003 but slowed in 2009 amid the global financial crisis.
Soledad Perez Duhalde of the Abeceb consultancy pointed in part to Brazil for the slowdown, saying all had expected that country's economy to rebound faster.
Friday's release of figures follows an IMF censure of Argentina earlier this month for failing to supply accurate economic data, the first time ever the global body has taken such an action against a member. It gave Buenos Aires until September 29 to resolve the problem.
Official Argentine statistics are sharply different from those private sector economists issue.
For instance, last month the government said that inflation in 2012 was 10.8 percent, while a group of private economists who collate their data put the rate at 25.6 percent.
Buenos Aires benefits from understating the data because a large part of its sovereign debt is indexed to inflation.
Brazil, an IMF board member and strategic ally of Argentina, criticized the censure as "counterproductive."
And in a tweet, Argentine President Cristina Kirchner suggested that her government's debt reduction policy "seems to be the real cause of anger from the IMF."
Argentina defaulted on some $100 billion in debt in 2001, and has since restructured its debt twice, covering around 75 percent of the nominal value of the bonds.