India's rice harvest may fall far faster than had been thought thanks to the weak monsoon rains, also expected to hurt production of corn and sorghum, although an export ban looks off the cards for now.

US Department of Agriculture staff in New Delhi slashed to a six-year low of 94m tonnes their forecast for rice production in India, the world's second-largest producer, after China.

The downgrade, to a level 6.0m tonnes below the official USDA forecast, reflected the weak start to the monsoon, which "at best can recover to 85% of normal [rainfall] based on the last 10 years' monthly precipitation data", the bureau said in a report.

Official Indian meteorologists last week acknowledged the monsoon set to prove "deficient", implying a shortfall of at least 10% from average levels.

For rice, the water shortage meant growers were likely to cut sowings by 2m hectares to 42m hectares.

"Planting progress is currently lagging behind last year's level by about 2m hectares, and the window of opportunity for planting rice in most states will be over by the second week of August," the briefing said.

"In a worst case scenario, if the monsoon rains remain deficient in August, production will almost certainly not achieve even that reduced level," of 94m tonnes.

Government to step in?

India's rice harvest has taken on particular global importance since top exporter Thailand initiated a stockpiling programme, supporting rural incomes but lowering supplies available for export.

India has exported more rice than Thailand in 2011-12, and will ship only 1m tonnes less in 2012-13, on current USDA estimates.

However, while India's government may thanks to weaker rice harvest hopes "explore additional market control measures", such as limits on hoarding and a ban on futures trading, to keep domestic prices in check it is "unlikely to impose any export control  measures on rice wheat and corn" unless production prospects deteriorate further.

"If rains remain deficient through August/September, the government may review exports of non-basmati rice, wheat from government stocks and corn, with an eye to an export ban," the USDA bureau said.

Wheat sale

The comments, which follow a caution from the United Nations Food and Agriculture Organization over the risk of Indian export curbs, came as the country revealed limited success in an effort to sell down part of its huge heat inventories.

India sold 100,000 tonnes to Toepfer, the German trading house, at $302 a tonne, and a further 20,000 tonnes at $296.68 per tonne.

Singapore-based trading company Starcom bought 70,000 tonnes, also at $296.68 per tonne, but bids for a further 50,000 tonnes were not accepted.

India is aiming to sell 2m tonnes of stocks, which swelled to 47.5m tonnes at the start of the month, nearly three times a target of 17.1m tonnes.