Motorists may have to wait months for fuel prices to come down, despite the US and Iran agreeing to a pause in fighting which includes reopening the Strait of Hormuz. In exchange for American attacks being put on hold for two weeks, Iran has agreed to allow tankers to resume travelling through the critical waterway, which before the war carried around one-fifth of the world's oil.While the American oil benchmark Brent Crude plunged 13 per cent to about $US95 a barrel, Australian petrol and diesel prices are unlikely to respond straight away, experts and industry insiders have told AAP. Australian Institute of Petroleum chief executive Malcolm Roberts, who represents major petrol companies including Ampol, BP, Mobil and Viva Energy, said the ceasefire was welcome but the effects would take some time to flow through supply chains. 'We would caution people from expecting this will have immediate effects on supply or prices in our region,' he said. 'It's going to take quite some time for global supply chains to reconnect.'