Oil extends weekly fall as glut bigger than thought

New York

OIL deepened its weekly decline as Goldman Sachs Group Inc said a global supply surplus could force prices to as low as US$20 a barrel.

Futures fell after two weeks of gains. Goldman said the world's oil glut is even bigger than it thought, according to an e-mailed report from the bank on Friday. Crude supplies outside Opec will decline next year by the most in more than two decades as the price rout curbs US shale output, according to the International Energy Agency.

Oil has fluctuated since slumping below US$40 a barrel three weeks ago as concern over slowing growth in China fuelled volatility in global markets. A Senate vote paved the way for US President Barack Obama to ease financial penalties for doing business with Iran, which would allow an increase in the nation's oil exports. US stockpiles continue to rise, even…