Oil fell to the lowest level in almost six years on Monday as signs that Saudi Arabia's new king will maintain its production policy and rising US crude stockpiles bolstered speculation that a global glut will persist.

Futures dropped as much as 2.7 percent in New York, extending a 6.4 percent slide last week. King Salman bin Abdulaziz, who took over after the death of King Abdullah on Friday, pledged to maintain the policies of his predecessor in a speech on Saudi national television. US inventories climbed to 383.5 million barrels last month, the highest level for December since 1930, the American Petroleum Institute reported.

Oil slumped almost 50 percent last year as the Organization of Petroleum Exporting Countries resisted calls to cut output even as the United States pumped at the fastest pace in more than three decades. Saudi Arabia, the world's biggest exporter, has chosen not to reduce supply and count instead on lower prices to stimulate demand, according to Mohammad Al Sabban, an adviser to the kingdom's petroleum minister from 1988 to 2013.