Donald Trump will declare the Iran nuclear deal as not being in America's national security interests and failing to protect international peace, the White House has said.

Mr Trump is to deliver a major speech outlining his new strategy on Iran later on Friday, which will include a broad and harsh critique of both the country and its supreme leader, Ayatollah Ali Khamenei.

In a statement released on Friday morning, the White House said Mr Trump had "approved a new strategy on Iran", one that "focuses on neutralising the Government of Iran’s destabilising influence and constraining its aggression, particularly its support for terrorism and militants".

Mr Trump's speech from the White House, to be delivered at 12.45pm EST (5.45pm BST), will outline specific faults he finds in the 2015 accord but will also focus on an array of Iran's troubling non-nuclear activities, the White House said. Those include Tehran's ballistic missile program, support for Syrian President Bashar al-Assad, Lebanon's Hezbollah movement and other groups that destabilise the region, including in Yemen.

Under US law, Mr Trump faces a Sunday deadline to notify Congress whether Iran is complying with the accord that was painstakingly negotiated over 18 months by the Obama administration and determine if it remains a national security priority. Although Trump will allow that Iran is living up to the letter of the agreement, he will make the case that the deal is fatally flawed and that its non-nuclear behaviour violates the spirit of the regional stability it was intended to encourage, officials and advisers told the Associated Press.

Mr Trump will instead ask Congress to amend or replace the legislation which requires him to certify Iran's compliance with the deal every 90 days.

Officials have said that Mr Trump hates the requirement more than the nuclear deal itself because it forces him to take a position every three months on what he has denounced as the worst deal in American history. That frequency has also irritated aides who have complained that they are spending inordinate amounts of time on certification at the expense of other issues.

The officials and advisers said Mr Trump will not call for a re-imposition of nuclear sanctions on Tehran. He will instead urge lawmakers to codify tough new requirements for Tehran to continue to benefit from the sanctions relief that it won in exchange for curbing its atomic programme. And he'll announce his long-anticipated intent to impose sanctions on portions of Iran's Revolutionary Guard Corps by designating them terrorist organisation under an existing executive order.

Separately, speaking in St Petersburg at an international parliamentary forum, Iran's parliament speaker Ali Larijani said it would be the end of the international nuclear deal if the US withdrew its support.

According to Russia's Tass news agency, Mr Larijani said such a collapse of the deal would lead to global chaos.