OIL prices tumbled about 6pc to a 4-week low on Friday (Jun 17) on worries that interest rate hikes by major central banks could slow the global economy and cut demand for energy. Also pressuring prices, the US dollar this week rose to its highest level since December 2002 against a basket of currencies, making oil more expensive for buyers using other currencies. Brent futures fell US$6.69 or 5.6pc to settle at $113.12 a barrel, while US West Texas Intermediate (WTI) crude fell $8.03 or 6.8pc to settle at $109.56. That was the lowest close for Brent since May 20 and the lowest for WTI since May 12. It was also the biggest daily percentage decline for Brent since early May and the biggest for WTI since late March. For the week, Brent futures declined for the first time in 5 weeks, while WTI dropped for the first time in 8 weeks. There will be no US trading on Monday, the Juneteenth holiday.