Iran will break the uranium stockpile limit set by Tehran's nuclear deal with world powers in the next 10 days, the spokesman for the country's atomic agency has said.

Key points: The announcement indicated Iran's determination to break from the landmark 2015 accord

The announcement indicated Iran's determination to break from the landmark 2015 accord The deal has steadily unravelled since the Trump administration re-imposed tough economic sanctions on Iran

The deal has steadily unravelled since the Trump administration re-imposed tough economic sanctions on Iran It comes in the wake of suspected attacks on two oil tankers in the Gulf of Oman

Behrouz Kamalvandi also warned that Iran has the need for uranium enriched up to 20 per cent, just a step away from weapons-grade levels.

The announcement indicated Iran's determination to break from the landmark 2015 accord, which has steadily unravelled since the Trump administration pulled the United States out of the deal last year and reimposed tough economic sanctions on Iran.

The US sanctions sent Iran's economy into freefall, and tensions between the two countries have steadily increased since then.

Mr Kamalvandi made the announcement while speaking to local journalists at Iran's Arak heavy water facility, in a media conference broadcast live on Iranian state television.

"We have quadrupled the rate of enrichment and even increased it more recently, so that in 10 days it will bypass the 300 kg limit," he said.

"There is still time … if European countries act."

Mr Kamalvandi said Tehran would increase uranium enrichment levels "based on the country's needs".

Iran needs 5 per cent enrichment for its nuclear power plant in the southern Iranian port of Bushehr and it also needs 20 per cent enrichment for a Tehran research reactor, the spokesman said.

Uranium enriched up to 20 per cent is only a step away from weapons-grade levels — something that worries nuclear nonproliferation experts.

The development comes in the wake of suspected attacks on two oil tankers in the Gulf of Oman last week that Washington has blamed on Iran.

Similar attacks in May were also blamed on Iran, though the country's Government denies any involvement.

ABC/wires