Consumer prices rose at the fastest rate since May, Reuters reported. A government report showed that rising energy prices helped increase the Consumer Price Index, and will most likely keep the Federal Reserve worries about inflation.

The CPI, the most widely used measure of inflation, increased at a 0.3 percent rate in September, after falling 0.1 percent in August, the Labor Department said.

Wall Street economists had projected a 0.2 percent increase for September consumer prices, but the actual rise was the highest since a 0.7 percent swell in May 2007. September’s CPI was up 2.8 percent from a year earlier. This marked the largest year-to-year increase since a 2.8 percent jump in March 2007, Labor Department officials said.

After three months of falling, energy prices rose 0.3 percent in September. Department officials reported that energy prices have ascended at an 11.7 percent annual rate for 2007.

The value of the dollar fell after September’s CPI information was released. The prices of government debt securities increased.