Inflation remained unchanged in the United States last month on a downturn in energy costs, the US Labour Department said Thursday.

On a seasonally adjusted basis, the consumer price index remained "virtually unchanged" in September from the previous month after falling 0.1 per cent in August. Prices increased 4.9 per cent year-over-year.

The steady inflation reflected a drop in energy prices, which fell 1.9 per cent in September after dipping 3.1 per cent in August.