US natural gas prices moved lower yesterday after weekly inventory data provided a major surprise. There was an unexpected increase in stocks instead of the forecast decline, with demand hit by warmer-than-expected winter weather.

Nymex February Henry Hub traded just over 6 cents lower at $9.59 per million British thermal units after the Energy Information Administration reported a 1bn cu ft increase in inventories in the week to December 30. Since mid-December, natural gas prices have fallen by almost 38 per cent as mild winter weather has reduced consumption.