US consumer prices surged in September for the second straight month, gaining 0.6 percent from August on the back of a sustained rise in gasoline prices, the Labor Department said Tuesday. But core prices -- which exclude volatile food and energy -- were up only 0.1 percent, and the year-on-year consumer price index (CPI) was up just 2.0 percent, leaving little pressure on the central bank to act to tame price rises. Prices rose at an 0.6 percent monthly rate for the second month running, driven by higher energy costs. In September gasoline prices were up 7.0 percent, and energy costs generally rose 4.5 percent. Auto and apparel prices fell, and other sectors showed very modest gains, tempering the overall CPI rise.