"This is very exciting for us," said a spokeswoman for Niki Trading Co., a still relatively new commodity trading firm. Niki surprised the US grain industry last fall by securing an order from the Government Trading Corp. of Iran for 3.55 million tonens of the US commodities.

Senior officials from the Treasury Department and the US agriculture department scheduled a Monday briefing at 2000 GMT on the new rules, the aide told Reuters. Spokeswomen for both departments declined to comment.

The United States announced on April 28 it would change US Sanctions policy to exempt food, medicine and medical equipment sales. The decision cleared the way for such sales to Iran, Libya and Sudan on a case-by-case basis, once new regulations were written.

Of the threecountries, Iran is considered the biggest potential market for US farm goods. Because of a severe drought, Iran's wheat imports are expected to double during the coming year to 6.0 million tonnes.

The new regulations come at a time of some turmoil in Iran. In recent weeks, thousands of students have taken part in demonstrations demanding greater political and social reform.

Despite the order that Iran placed last fall with Niki Trading, Iran's deputy trade minister Masoud Karbasian was quoted by Iranian newspapers on Monday as saying Tehran was unlikely to buy from the United States.

"We have never given serious consideration to buying grain from America, as prices are generally falling in world markets and we do not need to buy goods from America," Karbasian said.

"As far as we are concerned, the US Sanctions are still in place. We will accept to buy American goods only when we can export our products to the United States," he said.

But president of Niki Richard Bliss has expressed confidence aboutfilling Iran's order, which included 2.0 million tonnes of wheat, 4,00,000 tonnes of sugar, 4,00,000 tonnes of corn, 300,000 tonnes of rice, 2,50,000 tonnes of soybean oil and 2,00,000 tonnes of soybean meal.

"The bottom line is we're ready, willing and able to move forward. All we need is the go-ahead. Within a couple weeks of that, we expect to have consummated a deal," Bliss said in a Reuters interview last week.

Iran's State Livestock Affairs Logistics (SLAL) agency also is interested in buying "substantial quantities" of animal feed, Bliss said. And, Niki has been contacted by a number of poultry operations in Iran "looking for corn," he said.

Some US farm sectors that had been hoping to participate in the sales to Iran, Libya and Sudan may be left out.

The rules are expected to cover food items for human consumption and animal feed, a Clinton administration aide had said last week. That definition would prevent sales of the US cotton and tobacco to the three nations.

The Clinton administrationalso has decided on a "pretty straightforward, narrow definition" for medicine and medical equipment, the aide said.

But the new regulations are expected to please the US grain exporters, who had sought speedy procedures to take advantage of rapid changes in the commodities markets. Grain exporters want the administration to pre-approve grain sales, rather than insist on reviewing fully negotiated contracts.