The International Grains Council has raised its forecast for America's corn production this year by 8m tonnes (315m bushels), casting doubt on expectations that frost and a late harvest have caused significant damage.

The influential intergovernmental body raised to 330m tonnes (13.0bn bushels) its estimate of the US corn harvest, the main factor for an increase in its forecast for global grains production in 2009-10.

While the figure leaves the IGC data in line with official Washington statistics released three weeks ago, they follow frosts and heavy rains which have caused severe hold-ups to the US harvest, making it the slowest since records began in 1985.

Just 20% of the crop was in the silo as of last Sunday, compared with an average of 58%.

"Wet weather and freezing temperatures further delayed the US harvest, but record yields are expected to increase the crop to 330m tonnes," the IGC said.

Nonetheless, many traders have pencilled in corn crop losses of about 100m-200m bushels to weather damage.

Alaron, the US broker, said that with crops in many states, including Illinois, Indiana and Michigan remaining 10-20% immature as of last weekend, there was scope for cuts to official US production estimates.

"The growing season is over so [corn in] these states never fully developed," Alaron said.

Planting of the 2010 crop among northern hemisphere producers had "progressed well" although, thanks to lower prices, sowings were expected to decline year on year.

The total grain harvest would come in at 1.76bn tonnes, the IGC said, raising its estimate by 7m tonnes.