(Adds falls in exports, imports)
BUENOS AIRES, Sept 22 (Reuters) - Argentina's trade surplus shrank by a worse-than-expected 94.7 percent August from the same month a year earlier as lower commodity prices sparked a slump in export revenue, government data showed on Tuesday.
The trade surplus came in at $51 million, undershooting even the lowest estimate in a Reuters poll of analysts for $200 million. The median forecast in the poll was for a surplus of $352 million.
Argentina's government faces an acute hard currency shortage given that a long-running legal dispute with creditors has restricted its access to global capital markets.
It has relied on the trade surplus in recent years to boost dollar supplies on the tightly controlled currency market but that is shrinking due to regional economic slowdown and lower prices worldwide for the commodities Argentina exports.
In July, the surplus narrowed by 75 percent.
A breakdown of the government data on Tuesday showed exports tumbled 16 percent compared with the same month a year earlier due to a 15 percent drop in prices and a 2 percent fall in quantity exported.
Imports also fell due to the drop in prices, albeit less, by 3 percent.
The trade surplus for the first eight months of the year was $1.487 billion, the data showed, compared with $5.099 billion in the same period in 2014. (Reporting by Buenos Aires newsroom; Writing by Sarah Marsh; Editing by Meredith Mazzilli and Matthew Lewis)