Oil prices ticked lower but held above $56 on Monday as the IMF forecast energy costs to stay high for at least two years, while top exporter Saudi Arabia said Opec could decide at any time to add more supply to the market. US light crude for April delivery slipped 6 cents to $56.66 a barrel, less than $1 under the all-time peak at $57.60 struck last on Thursday.
The April contract is due to expire at the close of business on Monday and May crude futures on the New York Mercantile Exchange shed 8 cents to $57.16 a barrel.
Saudi Arabia continued to reassure dealers that there were ample supplies to meet robust demand, saying it had 1.5 million barrels per day (bpd) of spare production capacity, which could be sent to the world market immediately if needed.
"We can go up a million and a half barrels per day," Saudi Oil Minister Ali al-Naimi said. "The perception in the market is that there is not enough supply, which is untrue. There's plenty," Naimi said after meeting Philippine energy officials in Manila.
The kingdom, along with other members of the Opec producers' cartel, agreed last week to raise group output by 500,000 bpd to 27.5 million bpd with immediate effect to try to bring down prices from last week's records.
International Monetary Fund chief Rodrigo Rato warned on Saturday the world would have to live with lofty oil prices for at least the next two years because of strong demand and constraints in supply.
"We have to be aware that probably oil prices will stay high, although probably not at this level, in the next two years at least because of demand pressures there is certainly very strong demand in the world for oil and also because of certain supply constraints," Rato told reporters in New Delhi.
He said world economic growth was expected to be more than 4 percent this year but could come in lower if oil stayed at current levels or climbed higher.
Investment bank Societe Generale said it had upgraded its forecast for oil demand growth by 2.5 percent to 2.1 million bpd and had raised its price estimate to $49.50 a barrel for US crude from $45.80.
Saudi Arabia's Naimi said the Organisation of the Petroleum Exporting Countries could decide at any time whether to raise formal output limits by a second 500,000 bpd if prices failed to fall below $55.
"The president just had a meeting a week ago, he is looking at it right now and the possibility of consulting with other ministers," Naimi said, referring to Opec President Sheikh Ahmad al-Fahd al-Sabah.
Opec output is close to a 25-year high and non-Opec producers are pumping at full tilt, leaving little leeway in the supply chain for any output glitch.