Behrouz Kamalvandi of the Atomic Energy Organization of Iran made the remarks in a news conference carried on live television on Saturday. He spoke from a podium with advanced centrifuges standing next to him.

Iran has already breached the stockpile and enrichment level limits set by the deal, while stressing it could quickly revert back to the terms of the accord, if Europe delivers the sanctions relief promised in return for curbing Tehran's nuclear program.

Kamalvandi warned that Europe had little time left to save the deal. President Donald Trump withdrew America from the accord over a year ago before imposing crippling trade sanctions on Iran.

"As far as the other side does not implement their commitments, they should not expect Iran to fulfil its commitments," Kamalvandi said.

Kamalvandi said Iran had the ability to go beyond 20 per cent enrichment of uranium. Analysts say 20 per cent is just a short technical step away from 90 per cent enrichment, which is weapons-grade level.

Kamalvandi warned several times in his comments that Iran was rapidly approaching a point that would mean a full withdrawal from the deal.

"Our stockpile is quickly increasing, we hope they will come to their senses," he said.

However, he stressed that Iran would allow UN inspectors to continue to monitor sites in the country. A top official from the UN's International Atomic Energy Agency was expected to meet with Iranian officials in Tehran on Sunday.

Tensions between Iran and the US have risen in recent months that have seen mysterious attacks on oil tankers near the Strait of Hormuz, Iran shooting down a US military surveillance drone and other incidents across the wider Middle East.

Also on Saturday, satellite images showed a once-detained Iranian oil tanker pursued by the US appears to be off the coast of Syria, where Tehran reportedly promised the vessel would not go when authorities in Gibraltar agreed to release it several weeks ago.

The tanker Adrian Darya-1, formerly known as the Grace-1, turned off its Automatic Identification System late Monday, leading to speculation it would be heading to Syria.

Iranian and Syrian officials have not acknowledged the vessel's presence there. There was no immediate report in Iranian state media about the ship, though authorities earlier said the 2.1 million barrels of crude oil onboard had been sold to an unnamed buyer.

Australian Associated Press