US oil prices fell 62 cents to $46.56 a barrel in early electronic trade, putting them 6 percent below last week's two month high near $50.

Dealers who had braced for uncertainty at the weekend took profits after Iraq's first post-war poll and the Organisation of the Petroleum Exporting Countries' (Opec) policy meeting, both on Sunday, failed to yield any big surprises.

"The market had been boosted by Opec, Iraq and cold weather in the United States, but all that is ending," said Shun Maruyama, an analyst at UFJ Institute Ltd in Japan.

Opec ministers agreed to keep output limits unchanged at 27 million barrels per day (bpd) as near-$50 prices put a hold on any second-quarter supply tightening measures.

In Iraq, insurgents killed 35 people as millions went to the first multi-party polls in half a century, but oil exports from the southern terminals of Basra and Khor al-Amaya ran smoothly at 1.7 million bpd on Sunday, industry officials said.

Adding to the bearish mood, frigid conditions in the heating oil-consuming US Northeast are forecast to return to normal this week and remain warmer than usual the rest of winter, easing pressure on sub-par stockpiles.

Opec ministers meeting in Vienna sent their clearest signal yet that higher prices are here to stay, erasing last year's worry about the impact of $50-plus oil on the world's economic health.

"$50 oil will not play a big role in slowing up growth of the economy. Some analysts say even $60 oil will play a small role in affecting growth," said Opec President Sheikh Ahmad al-Fahd al-Sabah of Kuwait.

Opec formally abandoned its long-defunct $22-$28 price target and appears set to defend a price floor of $40 a barrel for US crude, a level that could be tested in the next few months.

AFP Adds: Traders were reassured by Opec's decision to maintain current production levels in the face of increased cold weather demand during the northern winter.

"No oil export infrastructure was attacked (on election day) so oil output from Iraq continues," said Victor Shum, an analyst at energy consulting firm Purvin and Gertz.

"Opec also announced they would continue to monitor the markets and take action if necessary, so that is a signal to the market they are willing to step in to defend prices," Shum added.

During the meet in Vienna, Opec agreed to maintain "currently agreed production levels" of 27 million barrels per day (bpd).