Saudi Arabia has stepped up its bellicose rhetoric against Iran, with the powerful crown prince accusing the country’s regional arch-rival of supplying missiles to Yemeni rebels in “an act of war against the kingdom”. Mohammed bin Salman, whose weekend crackdown on corruption was endorsed by US President Donald Trump, accused Iran of “direct military aggression” according to the state news agency. Saudi air defences on Saturday intercepted a ballistic missile fired from Yemen, causing debris to fall on an uninhabited area near Riyadh’s airport. Javad Zarif, Iran’s foreign minister, on Monday accused Saudi Arabia of engaging in wars of aggression and regional bullying, describing its actions as “destabilising behaviour and risky provocations”, with Riyadh blaming the consequences on the Islamic republic. The war of words across the Gulf has sent oil prices gyrating, with brent crude hitting a new two-year high of $64.65 in morning London trading before sharply selling off before midday. It also ratchets up the stakes in the stalemated proxy conflict in Yemen, where Saudi Arabia in 2015 led a coalition of Sunni states against the Houthi rebels, who are allied to Shia-led Iran. The conflict, leaving more than 10,000 dead, has created a humanitarian crisis in the impoverished Arab state.