Natural gas futures extended their earlier losses Thursday after a government report showed the largest weekly build in U.S. inventories so far this year.

Natural gas for June delivery recently traded 12.2 cents, or 2.79%, lower, at $4.257 a million British thermal units on the New York Mercantile Exchange.

The contract traded around $4.31/MMBtu before the report, though it went about 5 cents lower moments before the data was released.

The Energy Information Administration said U.S. gas stockpiles rose by 105 billion cubic feet last week, well above the 93-bcf average estimate of gas analysts and traders in a Dow Jones Newswires survey.

The injection came in larger than last year's 100-bcf build and the five-year average increase of 95 bcf on the week.

Inventories as of May 20 stood at 2.024 trillion cubic feet, 1.3% below the five-year average, and 10.2% below 2010 levels.