Overall consumer-level inflation surged more than expected last month as energy prices increased, but the key core rate was only half the advance analysts had been anticipating.

The government's consumer price index for May rose 0.7% and had its biggest move since September 2005. Economists, on average, were looking for a 0.6% climb.

However, the core CPI, which excludes food and energy, ticked up only 0.1%, whereas the forecast was for a 0.2% rise.

Compared with a year ago, consumer prices were up 2.7% in total. The core rate was higher by 2.2%.