Iran failed to find any buyers on Monday in its latest attempt to sell oil to private companies for export on the energy exchange, state media reported, in a setback to Tehran's efforts to bypass US sanctions.
Crude oil trade is state-controlled in Iran, but to try to work around US sanctions, the government last year started to sell crude to private buyers through the exchange.
However, there were no buyers on Monday for the one million barrels the National Iranian Oil Company (NIOC) offered on the exchange at a starting price of $52 a barrel.
In October, before US sanctions came into force, Iran sold 280,000 barrels at $74 apiece of the one million barrels it offered on the exchange. Two weeks later it sold 700,000 barrels at $64 each.
Iran has not revealed the identity of the private buyers in the energy exchange because they might be targeted by US penalties.
The buyers in the first two rounds had to settle 20 percent of the payment in rials and 80 percent in foreign currencies. However, in the last round, all purchases could be paid with rials.
Washington re-introduced sanctions on Iran's oil exports on Nov. 4 after withdrawing from a 2015 multinational deal that had lifted sanctions in return for limits on Iran's nuclear programme.
Iran's vice president on Monday said that Iran can still find buyers for its oil.
"Despite US plots to stop Iranian oil sales ... we have managed to sell as much crude as we need," Eshaq Jahangiri was quoted as saying by SHANA, the oil ministry's news agency.