Global oil demand will be sluggish throughout 2013 as economic expansion remains tepid, the West's energy agency said on Wednesday, also predicting comfortable oil supply levels, which could alleviate oil price pressures on consumers.

"Global demand growth is expected to stay relatively sluggish through 2013, based on the continued assumption of tepid global economic expansion," the International Energy Agency said in a monthly report.

It forecast global oil demand growth for 2013 at 865,000 barrels per day, 110,000 bpd higher than in its previous report, taking consumption up to an average of 90.5 million barrels per day.

On the supply front, the IEA said spectacular growth in U.S. production on the back of a boom in shale oil, which will be one of the top developments for the market in 2013. The United States will contribute heavily to an aggregate non-OPEC increase in output of 890,000 bpd to 54.2 million bpd in 2013, IEA said.

The IEA also said its forecast for demand for OPEC oil was unchanged for 2013 at 29.9 million barrels per day, much higher than the group's current production of 31.22 million in November.

It said, however, that it did not expect OPEC ministers, who are meeting in Vienna on Wednesday, to decide on any production cuts but that they would probably roll over their current 30 million bpd target, given relatively robust oil prices.

"Leading up to the gathering, the majority of ministers have signaled the status quo will be maintained despite production this year averaging 1.5 million bpd above the current target," the IEA said.

"Indeed, Brent futures prices are on track to surpass 2011 record levels this year, buoyed by heightened political risks in key producing countries, both in OPEC and non-OPEC countries," it said.

The IEA also said it believed Iranian production had edged lower in November, down 20,000 bpd to 2.70 million bpd, and that preliminary shipping data indicated volumes may fall further in December due to international sanctions.

"Iranian crude exports are expected to turn lower next month and into the New Year — reaching a level closer to 1 million bpd — as EU and Asian countries reduce further their crude imports from Iran in order to secure continued access to the US financial system," it said.