(Adds Statistics Office quotes)
BUENOS AIRES, May 22 (Reuters) - Argentina's trade surplus plunged 69.2 percent in April from the same month a year earlier to $252 million due to a fall in commodity prices, official data showed on Friday, sharply undershooting market expectations.
Analysts polled by Reuters had forecast a much more moderate trade surplus slide in Latin America's third largest economy, to $698 million from $818 million in April 2014.
"The drop in exports is exclusively the consequence of the fall in prices," the Statistics Office said in a statement. "If prices had been the same as the same month a year earlier, the trade balance would have reached a surplus of $1.002 billion."
Expectations of a bumper harvest in Latin America and the United States have weighed this year on international prices for Argentina's top exports of soy and corn.
The value of exports fell 19 percent, far outpacing a 12 percent slide in imports, the Statistics Office data showed.
The decline in the trade surplus is a blow to President Cristina Fernandez's government, which relies heavily on the surplus to boost dollar supplies on the tightly controlled currency market.
That said, the government has managed to bolster foreign reserves in recent months through a bond auction and unconventional financing measures such as a currency swaps with China. There are only a few more months until presidential elections in October. (Reporting by Sarah Marsh; Additional reporting by Eliana Raszewski; Editing by Meredith Mazzilli)