Prince Mohammed bin Salman, Saudi Arabia’s ambitious 31-year-old defence minister, was made heir to the throne yesterday in an endorsement of his plans to overhaul the kingdom's economy and aggressively confront Iran in the Middle East.

He gained the title of crown prince at the expense of his older cousin, Mohammed bin Nayaf, who was stripped of his position as the first in line to the the throne and also lost his job as Saudi Arabia’s interior minister.

The move ends any uncertainty over who will succeed King Salman, who is 81 and in poor health, and puts the future of Saudi Arabia in the hands of a young modernising prince who could potentially rule for decades.

Prince Mohammed, often referred to by his initials “MBS”, became defence minister aged 29 but his father also gave him broad powers over the economy and on foreign affairs.