(CNN) -- An additional six countries and Taiwan have significantly reduced their imports of Iranian crude oil and will not face tough sanctions from the United States, according to a statement released Monday by Secretary of State Hillary Clinton.
India, Malaysia, South Korea, South Africa, Sri Lanka, Turkey and Taiwan now join 11 other countries that have met requirements set by U.S. law to reduce oil purchases from Iran to avoid a cutoff in access to the U.S. financial system.
Japan and 10 countries from the European Union secured waivers from U.S. sanctions in March.
"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," Clinton said in a statement.
The American sanctions target any transactions of Iranian oil processed through Iran's central bank. The sanctions would go into effect on June 28.
Conspicuously missing from the list is China, one of the largest importers of Iranian oil products.
In a briefing for reporters, a senior U.S. administration official touted constructive dialogue with China on Iran sanctions and said it would be premature to comment on ongoing discussions with China.
"We may have different perceptions of sanctions at different times, but one of the things that has been very important is that China has agreed to this dual track process of pressure as well as persuasion," said the official, who spoke on the condition of anonymity.
Earlier this year, China reduced its purchases by as much as 50%, but that decision was driven mostly by a pricing dispute over existing contracts China had with Iran.
China has said it does not support the U.S. sanctions and has not asked for a waiver.
According to International Atomic Energy Agency figures cited by the U.S. administration official, the sanctions have had an impact on Iran oil exports.
In 2011, Iran exported approximately 2.5 million barrels of oil a day. Current estimates show a drop to between 1.2 million and 1.8 million barrels a day.
"You have from Europe to Asia to South Asia, a very significant number of major economies that are allowing us to heighten the pressure on the Iranian government and to sharpen the choice to the Iranian government that as their chief revenue source continues to be dried up through this international action, they can continue down the path of growing economic impact and international isolation, or they can shift course and come in line with their obligations," the U.S. official said.
The so-called P5+1 group of the United States, Russia, China, France, Great Britain and Germany are scheduled to meet with Iranian officials in Moscow on June 18. Those who follow the talks are skeptical that there will be any breakthrough that will lead to Iran changing it's nuclear ambitions and preventing additional sanctions from going into effect. Besides the U.S. sanctions, the European Union will impose a full embargo on all Iranian oil as of July first.