The United States will exempt seven economies including India, South Korea and Turkey from the Iran oil sanctions, as a result of their significant reduction of oil purchase from Tehran, Secretary of State Hillary Clinton announced on Monday.

In a statement released by the State Department, Clinton said the seven economies are India, Malaysia, Republic of Korea, South Africa, Sri Lanka, Turkey and Taiwan, adding the decision was made because they "have all significantly reduced their volume of crude oil purchases from Iran."

These economies will join the 11 countries, including Japan and some European countries, that were put on the exemption list in March.

U.S. President Barack Obama signed a bill at the end of last year, expanding U.S. sanctions against Iran to cover its central bank and financial sector, a move that allows penalties on foreign banks that settle oil imports with the Iranian central bank.

Clinton said the sanctions seek to prevent Tehran from acquiring a nuclear weapon and to force it to comply with its international obligations.

The law, however, offers waivers to firms from countries that significantly reduce their crude imports from Iran.

"Today's announcement underscores the success of our sanctions implementation," said Clinton.

"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," said the U.S. diplomat.

She reiterated U.S. commitment to a "dual-track policy" which uses both channels of diplomacy and sanctions to deal with Iran.

"Iran has the ability to address these concerns by taking concrete steps during the next round of talks in Moscow," Clinton said, referring to the new round of nuclear talks between Iran and the six world powers -- Russia, China, the United States, Britain, France and Germany -- which is scheduled on June 18-19.

China and Russia have called for a peaceful resolution to Iran' s nuclear issue through dialogue and negotiation, according to a joint statement released by the two countries last Wednesday during Russian President Vladimir Putin's three-day state visit to China.

China and Russia oppose the use of, or threats of using, force on the issue, said the statement, adding that they do not agree on exerting excessive pressure and imposing any unilateral sanctions against Iran, but advocate efforts to promote peace and facilitate talks on Iran's nuclear issue.