(Adds comparison to monthly indicator, background on GDP warrants, revision to 2016 figure)
BUENOS AIRES, March 21 (Reuters) - Argentina's economy expanded 2.9 percent in 2017 from the prior year and 3.9 percent in the fourth quarter versus the same period in 2016, the Indec statistics agency said on Wednesday.
The year-over-year figure was slightly above the 2.8 percent annual growth rate given last month by Argentina's monthly economic activity indicator, seen as a proxy for gross domestic product.
The country's GDP figures are closely watched by holders of the country's so-called GDP warrants, which pay out in the event the economy grows 3 percent or more. With growth of 2.9 percent, Argentina would narrowly avoid a payment for 2017, though that will not be confirmed until the figure is revised in the second half of this year.
Indec also revised its estimate for 2016 GDP to a contraction of 1.8 percent, compared with a 2.2 percent contraction reported previously. (Reporting by Luc Cohen; Editing by Steve Orlofsky)