"I think a couple of consignments were bought for corn, barley and soymeal but probably well below the tender volumes," one trader said. "Sanctions are still making it very difficult to offer in Iran's tenders."

SLAL had issued international tenders to purchase up to 300,000 tonnes of animal feed barley, 300,000 tonnes of feed corn and 300,000 tonnes of soymeal.

The grains were sought for shipment in April, May and June.

"I think some South American corn and soymeal was purchased along with some barley, probably from the Black Sea," another trader said. "But I think purchases were well under what they sought in the tenders."

"Several of the big-name trading houses did not take part because of the problems with trade finance with Iran because of sanctions. This is still a headache."

Under the sanctions, reimposed by Washington last year over Iran's nuclear programme, the Islamic republic is blocked from the global financial system. Food, medicine and other humanitarian supplies including animal feeds are exempt.

"Trade finance with Iran for grains is possible but the regulations are hardly transparent and risks look high," the second trader said.

Sanctions continue to cause difficulties in other commodity trade including oil.