Oil prices have briefly fallen below 30 dollars a barrel on international markets for the first time since April 2004, before recovering again. Brent crude, used as an international benchmark, fell as low as 29.96 dollars, but bounced back to trade at 30.22 dollars. Oil prices have fallen by 70 per cent in the past 15 months.Earlier, Russia's Prime Minister, Dmitry Medvedev, warned tumbling oil prices could force his country to revise its 2016 budget. Taxes from oil and gas generates about half the Russian government's revenue.