Consumer prices are up slightly over last year driven by climbing food and energy costs, according to a government report released Friday.

The Consumer Price Index, a key measure of inflation, rose 1.1 percent over the last 12 months ending in September, the Bureau of Labor Statistics said Friday. Any number above zero means prices are rising, but a rate around 1 percent is considered very slow growth.

The latest number is unchanged from August, but when food and energy prices are stripped out, and the so-called core CPI is up slightly.

Core CPI rose at a 0.8 percent annual rate in September, after coming in completely flat in August.

Shortly ahead of the report, Federal Reserve Chairman Ben Bernanke gave a speech on the “low inflation environment,“ saying inflation trends will likely “remain subdued for some time.“

The CPI report is closely watched this month by economists and policymakers alike, because the government will use the data to determine whether Social Security beneficiaries will get a cost of living increase in 2011.

The government is expected to make an announcement about the cost of living adjustment later Friday.

September: For the month, overall CPI rose 0.1 percent, lower than expectations.

Prices were expected to have increased 0.2 percent in September, after climbing 0.3 percent the previous month, according to consensus estimates from Briefing.com.

Core CPI for the month was flat. Economists had expected it to have inched up 0.1 percent, after rising the same amount in August.