A pump jack is seen at sunrise near Bakersfield, California, on October 14, 2014. Reuters/Lucy Nicholson

(Reuters) - Brent crude oil slipped on Friday to below $63 a barrel, its lowest since July 2009, on persistent concerns over a global supply glut and a sluggish demand outlook.

Brent is down roughly 9 percent this week, some 45 percent below its June peak above $115 per barrel.

Oil prices will likely come under further downward pressure, the International Energy Agency said as it cut its outlook for demand growth in 2015 and predicted that healthy non-OPEC supply gains were poised to aggravate the glut.

The agency, which coordinates the energy policies of industrialized countries, cut its outlook for global oil demand growth for 2015 by 230,000 barrels per day (bpd) to 0.9 million bpd on expectations for lower fuel consumption in Russia and other oil-exporting countries.

"It spells out the main scenarios that are in the market and said that stockpiles will be substantially bigger in the first half of 2015," said Bjarne Schieldrop, chief commodity analyst for SEB in Oslo.

The Organization