Sales of non-food items rose 1.6% on the month in April, while fuel and food sales increased 0.9% and 0.2% on the month, respectively.
The data are adjusted for the number of working days and seasonal factors.
In annual terms, adjusted retail sales advanced 3.4% in April, largely boosted by an 11.1% increase in fuel sales, INS said.
Food sales rose 1.9% on the year in April, while non-food sales advanced 1.8%.
In January-April, retail sales were up 4.2% compared with the year-earlier period.
In unadjusted data, retail sales increased 2.6% in April from a month earlier and were up 3.4% compared with the same month of 2011.