New Delhi, Oct 15: India's merchandise exports declined by 2.15 per cent in September on a year-on-year basis, official data showed on Monday.According to data released by the Ministry of Commerce and Industry, the decline in exports was due to high base effect with September 2017 "being an abnormally high growth month of about 26 per cent in US dollar terms due to the imminent cut off then for drawbacks at pre-GST rates". "This is a temporary out of trend phenomenon. Exporters continue to be resurgent with their realised incomes having gone up by almost 10 per cent. October 2018 figures promise to be as per the ongoing six-month trend again,"the Ministry said in its review statement.As per the data, petroleum products, organic and inorganic chemicals and drugs and pharmaceuticals commodity groups showed a high export growth during the month under review.On the other hand, imports in September exhibited a positive growth of 10.45 per cent."Merchandise trade deficit is $13.98 billion in September 2018, the lowest in last 5 months, despite high oil prices," the review statement said.