Core sector grew 7.9% in Sept, compared with 3.1% a year ago, driven by strong performance in electricity, cement and refinery products and aided by a favourable base as well, official data released Tuesday showed. Sequentially, the growth marked acceleration from an upwardly revised figure of 5.9% in Aug. This is the strongest performance of the core sector in the new series with the revised base year.Output in the energy-dominant industries like natural gas (-4.6%), crude oil (-1.4%) and fertilisers (-11.7%) saw continued sequential contraction, reflecting the impact of the prolonged conflict in West Asia. Output in the refinery products (10.3%) and coal (10.7%), however, saw acceleration during the month.Output in the infrastructure-dominant industries such as electricity (11.4%) and steel (4.9%) showed positive growth in Sept. In the newly added iron ore industry, output further accelerated (18.4%) during the month.Bank of Baroda chief economist Madan Sabnavis said Sept figures highlight buoyancy in infrastructure where govt has been spending.