Oil prices declined on Monday after US-Iran talks concluded in Switzerland with Tehran saying it had secured waivers for oil and petrochemical exports, easing worries about a supply shortage in global markets. Brent crude fell $1.68, or 2.09 per cent, to $78.89 a barrel by 0633 GMT (11:33am PKT). Prices had climbed to $82.30 at the start of trading, fuelled by a bumpy start to the talks with threats from US President Donald Trump to restart the war on Iran and Tehran’s announcement it had again closed the Strait of Hormuz.