WASHINGTON: US seeking to pressure China is moving to cut its imports of Iranian oil, tracking earlier efforts by countries such as India, Japan and South Korea which won them exemptions from tough new US sanctions, Secretary of State Hillary Clinton said on Wednesday.

The United States has already exempted a number of major countries from the new sanctions, which it may impose starting on June 28 as Washington's most ambitious measure yet to force Iran to curtail its nuclear program by reducing its oil export sales.

China, which alone buys as much as a fifth of Iran's crude exports has not yet been granted a similar reprieve, but Clinton hinted on Wednesday that one could be in the works.

“We've seen China slowly but surely take actions,” Clinton said in an appearance with former US Secretary of State James Baker, detailing the US-led effort to sanction Iran for its nuclear program.

“I have to certify under American laws whether or not countries are reducing their purchases of crude oil from Iran and I was able to certify that India was, Japan was, South Korea was,” Clinton said.

“And we think, based on the latest data, that China is also moving in that direction,” Clinton said.

Pledging to Cut Purchases

The United States and the European Union believe Iran is trying to build nuclear weapons. Tehran says the program is strictly for civilian purposes.

Beyond the 27-country EU, which has banned Iranian imports from July under separate sanctions, other buyers of Iran's crude have pledged to cut purchases by up to a fifth.

Turkey, South Africa, Taiwan, Malaysia and Sri Lanka will also be exempt from the sanctions, while 10 EU countries had been granted exceptions in March.

Banks and other institutions in the economies that received waivers will be given a six-month break from the threat of being cut off from the US financial system under sanctions signed late last year by President Barack Obama.

China, Japan, India and South Korea cut imports by about a fifth from the 1.45 million barrels per day they were buying a year ago as they prepared for the sanctions to come into effect.

Analysts say Obama must tread a fine line between tightening the screws on Tehran and triggering a squeeze on global oil supplies that could tip the US economy back into recession.

Backers of tough sanctions on Tehran believe China has received clandestine cargoes of oil from Iran, which has disabled tracking devices on some of its shipments.

Obama is under pressure from Congress, which may pass even tougher sanctions on Iran.

US officials say the dialogue with China - a key U.S. trading partner - has been constructive, leading many to believe that China will eventually win an exemption.