A former deputy director of the CIA has criticised Donald Trump’s decision not to re-certify the 2015 nuclear agreement between Iran and six world powers.

John McLaughlin said it was one of the President's "worst decisions" and would "shred" America's credibility.

“Iran speech - one of Trump's worst decisions: feeds Iran hardliners, splits allies, shreds US credibility, roils congress, gift to Russia,” he wrote on Twitter.

“Trump could combat Iran's testing of missiles etc without touching nuclear deal,” he continued.

John McLaughlin at the CIA headquarters in Langley, Virginia, in 2004 (Getty)

“But needs POTUS [President of the United States] discipline, hard work so far lacking.”

The Obama-era deal lifted crippling international sanctions on Iran in exchange for Iran’s agreement to restrict its nuclear programme for at least 10 years.

In a speech on Friday, Mr Trump said removing sanctions had given the “fanatical regime” in Iran a financial boost, increasing its ability to fund terrorism. He accused Iran of spreading “death, destruction and chaos around the globe”.

Mr Trump said he would not re-certify Iran’s compliance with the agreement, formally known as the Joint Comprehensive Plan of Action (JCPOA). He threatened to terminate the agreement unless Congress devised a deal placing tougher requirements on Iran.

“We will not continue down a path whose predictable conclusion is more violence, more terror and the very real threat of Iran's nuclear breakout,” he said.

Iran announced in September it had successfully tested a ballistic missile and claimed its tests did not contravene JCPOA. But a UN resolution asks Iran not to develop any ballistic missile capable of carrying nuclear weapons.

Mr Trump's speech "hands a tool to Iran's hardliners who attacked Iran’s more pragmatic president Rouhani for entering the deal", Mr McLaughlin wrote in The Cipher.

Five of the six other parties in the deal, including the EU, UK, France, Germany, Russia, have declared their continuing support for the agreement following Mr Trump's announcement. The sixth party, China, called on the US before Friday to preserve the agreement.

“Russia of course does not support the US position, nor does China,” pro-Kremlin MP Alexi Pushkov told Russia’s state-run Rossiya-24 TV station.

“So Trump will be left in proud isolation in an attempt to improve his image among his own supporters.”

However, US allies Israel and Saudi Arabia have come out in support of Trump’s decision.

Mr McLaughlin previously said Mr Trump’s address to 40,000 Boy Scouts at their annual meeting “had the feel of a third world authoritarian’s youth rally”.

Mr McLaughlin was deputy director of the CIA under Presidents Bill Clinton and George W Bush, then acting director.