Just a week after declaring a proposed agreement with Iran "largely finalised", US President Donald Trump has reportedly sent the Iran deal back for revisions, prolonging negotiations and casting fresh uncertainty over efforts to end the conflict.

The US and Iran have reached a tentative deal, but final approval hinges on former President Donald Trump's sign-off, with minor language issues still under discussion.

President confirms deal will reopen Strait of Hormuz after months-long stalemate that has devastated global economy