President Barack Obama has renewed unilateral US restrictions on purchases of oil and oil products from Iran.
In a decree, issued by his office, the US president said that global economic conditions, increased oil production by certain countries, and the level of (oil) spare capacity had allowed him to take the decision.
Saudi Arabia, a key US ally in the Middle East, has ramped up production leading to a crash in crude prices.
I determine that there is a sufficient supply of petroleum and petroleum products from countries other than Iran to permit a significant reduction in the volume of petroleum and petroleum products purchased from Iran by or through foreign financial institutions, Obama said in his statement.
The statement also referred to a US measure which forbids transactions with Iran.
Under the measure, foreign companies are cut off from the US financial system and face sanctions if they engage in transactions with Irans financial institutions.
However, a preliminary agreement reached in Nov. 2013 allows Iran to sell around 1 million barrels per day of crude oil.
The US restrictions fly in the face of that agreement under which no new sanctions should be imposed on the Islamic Republic.
Washington contends the agreement does not include renewal of the previous restrictions.
The US and five other countries are currently discussing a possible final agreement with Iran by the end of June.
Iran says any deal should envisage immediate removal of all sanctions, with the US saying they should be lifted gradually.