Oil prices tumbled to within a whisker of $30 a barrel on Tuesday, extending a savage new year sell-off as BP axed thousands of jobs and Brazil’s Petrobras cut tens of billions of dollars in spending. Signalling that it expects no let-up in a market downturn being likened to the slump of the 1980s, the UK-based energy major announced 4,000 job cuts across its exploration and production business, including hundreds in its hard-hit North Sea operations. The cuts came as the price of internationally traded Brent crude on Tuesday sank to $30.34 a barrel, near 12-year lows, taking its decline since the summer of 2014 to more than 70 per cent. Daniel Yergin, author of a history of oil, ‘The Prize’, told the Financial Times: “The supercycle in commodities is ending in great pain. The big worry is what’s really going to happen to the world economy.”