The US has granted seven further countries, including Sri Lanka, exemptions from sanctions for importing Iranian oil.
South Africa, India, South Korea, Sri Lanka, Taiwan and Turkey were given a waiver from meeting a US deadline, which is looming at the end of this month, to reduce imports from Iran.
Countries, which haven’t been granted an exemption and fail to reduce imports, will be cut off from the US financial system.
Japan and 10 EU states were granted exemptions from the sanctions, imposed by Congress in December last year, in March.
US Secretary of State, Hillary Clinton, said in a statement:
"By reducing Iran's oil sales, we are sending a decisive message to Iran's leaders: Until they take concrete actions to satisfy the concerns of the international community, they will continue to face increasing isolation and pressure,"
China remains under the threat of sanctions and is still under pressure to reduce their reliance on Iranian oil.