(Adds budget deficit context, comparative data)
BUENOS AIRES, Nov 19 (Reuters) - Argentina had a primary budget deficit of 4.26 billion pesos ($500 million) in September, according to economy ministry data released on Wednesday, versus a surplus of 412.5 million pesos in September 2013.
It was the first primary budget deficit since Argentina registered a negative balance of 286.8 million pesos in June.
The primary budget balance, which measures government spending relative to income and does not include interest payments on outstanding debt, is followed closely by the markets as an indicator of Argentina's ability to meet its financial obligations.
The South American grains exporting country is struggling with high inflation, a stagnant economy and faces a special financing challenge due to being locked out of the global bond market since its 2002 sovereign debt default.
($1 = 8.515 pesos ARS=RASL)
Reporting by Eliana Raszewski Editing by; W Simon