Oil slips as traders watch for U.S. Fed decision and rate guidance

​Oil edged lower after a four-day rally of almost six per cent as traders wait on Wednesday's U.S. interest-rate decision and guidance as to whether there will be further increases this year.

West Texas Intermediate traded near US$79 a barrel, slipping from its highest close since mid-April. The gains have been fueled by signs that the global market is starting to tighten, and moves by China's leadership revive growth in the world's largest crude importer after its recovery faltered.

The Federal Reserve is expected to raise borrowing costs to the highest level in 22 years later Wednesday, while at the same time retaining a tightening bias that signals the possibility of another move upward later this year. Higher rates risk slowing the economy and hurting energy consumption.