Trump imposes new 'maximum pressure' sanctions on Iran as tensions escalate

US President Donald Trump targeted Iran's steel and mining sectors on Wednesday in his latest tough sanctions days after Washington dispatched an aircraft carrier bombers to the Arabian Gulf.

The announcement came hours after Iran said it was suspending some limits set by a multinational nuclear deal - on the one-year anniversary of Trump's pullout from the accord.

The White House said it was imposing sanctions on all trade of Iran's iron, steel, aluminum and copper, the country's biggest export after oil - which the US is already working to halt completely.

"Tehran can expect further actions unless it fundamentally alters its conduct," Trump said in a statement.

He said a "maximum pressure" campaign on the Iranian government would continue until it stops "supporting terror groups, ends destabilising activities in the region, gives up any nuclear weapons efforts and ends any development of ballistic missiles".

But in a switch in tone, Trump said he was also willing to negotiate.

"I look forward to someday meeting with the leaders of Iran in order to work out an agreement and, very importantly, taking steps to give Iran the future it deserves," he said.

The US, Germany, Britain, France, Russia, China and the European Union signed a deal with Iran in 2015 that lifted international sanctions in exchange for Tehran limiting its nuclear programme.

Trump pulled out of the agreement, which he called "the worst deal in history." The administration then re-imposed crippling economic sanctions on Iran that had been lifted under the agreement.

The other nations have remained in the deal and have tried to provide Iran with enough economic incentives to keep the agreement alive.

The US said on Tuesday that it deployed massive B-52 bombers to the Gulf in response over what it described as a new threat from Tehran.