NEW DELHI: The United States has imposed its "toughest ever" sanctions against Iran on Monday. President Donald Trump's administration reinstated all sanctions lifted under the 2015 nuclear deal, targeting both Iran and countries that trade with it. US Secretary of State Mike Pompeo announced on Monday that Washington was exempting India from the sanctions on importing oil from Iran. Pompeo said the US will continue to negotiate with India and the seven other countries receiving the six-month exemption to get them to cut their Iranian imports to zero. The other countries receiving the exemptions Pompeo announced at a news conference with foreign correspondents in Washington were China, Greece, Italy, Turkey, South Korea, Taiwan and Japan.

The Trump administration said it has asked these countries including Turkey, Iraq, Italy, Japan and South Korea to bring down their oil purchase to zero as soon as possible.

The reimposition of US sanctions on Iran, Pompeo asserted are the toughest ever on this country. "They're aimed at a singular purpose, denying the world's largest state sponsor of terrorists the capacity to do things like they did this past couple weeks, attempted assassination campaign in the heart of Europe," he said.

More than 700 individuals, entities, vessels and aircraft were now on the sanctions list, including major banks, oil exporters and shipping companies. The measures will make it difficult to do business with the oil-rich nation.

"These sanctions have already had an enormous impact. We've already reduced Iranian crude oil experts by over a million barrels per day. That number will fall farther. There's a handful of places were countries that have already made significant reductions in their crude oil exports need a little bit more time to get to zero, and we're going to provide that to them," he said.

In July, US President Donald Trump announced he was pulling out of the nuclear deal signed in 2015 by the five permanent members of the United Nations Security Council, Germany and the European Union with Iran to end its nuclear weapons programme.

Trump said the sanctions that had been lifted after the agreement would be reimposed and the oil trade would be targeted starting Monday.

India imported from Iran nearly 10 per cent of the total of 220 million metric tonnes of crude oil it imported during 2017-18. Since the reimposition of sanctions were announced, India has been cutting back on the Iranian imports.

The UK, Germany and France -- which were among the five countries still committed to the nuclear pact -- objected to the sanctions. They promised to support European firms that do "legitimate business" with Iran and set up an alternative payment mechanism that will help companies trade without facing US penalties.

On Sunday, thousands of Iranians chanting "Death to America" rallied, rejecting calls for talks. The rallies coincided with the siege of the US Embassy on November 4, 1979. A total of 52 Americans were held hostage in the Embassy for 444 days and the two countries have been enemies ever since.

(With inputs from Agencies)