Natural gas futures American prices fell by around 4% on Thursday, following a report showing that Energy companies added more gas to inventories than expected last week last, when the mild weather maintained the demand for heating and air conditioning at a low level.

Gas futures contracts for October deliveries on the New York Mercantile Exchange fell by 10.9% cents, or 3.5%, to 2.991 USD per million British thermal units (MMBtu) at 10:32 EDT (14:32 GMT).

The American Information Agency on Energy (EIA) said that energy companies injected 90 billion cubic feet (bcf) of gas in inventories during the week ended on September 12. This was the largest weekly increase since June.

This figure is over 80 billion. cubic feet predicted by analysts in a Reuters poll, compared to a increase of 56 billion cubic feet in the same week last year and a average production of 74 billion cubic feet over the last five years. On the spot market, gas prices at the Waha Hub, in the shale Permian from West Texas, remained negative for the third day consecutive this week, pipeline maintenance, in particular that of Kinder Morgan's El Paso pipeline connecting Texas to California, continuing to trap gas in the country's largest oil basin.

The average volume of gas delivered to eight major American LNG export plants declined to settle at 15.7 billion cubic feet per day since the beginning of September, compared to 15.8 billion cubic feet per day in August. For comparison, the monthly record of 16.0 billion cubic feet per day was reached in April.

In other LNG news, the plant 0.8 billion cubic feet per day from Berkshire Hathaway Energy in Cove Point, Maryland, is expected to close soon for about a month for the annual fall maintenance planned.