Nymex crude fell below $91.50 a barrel, while Brent crude held above $98 a barrel for the fourth session on Monday, supported by a strong equities market and a persistently weak dollar.

US crude for February delivery slipped 1 cent to $91.39 a barrel by 0257 GMT, while Brent March values rose 17 cents to $98.55. The spreads between the two values having narrowed to less than $6.50 a barrel after hitting over $8.00 a barrel on Friday, making that the highest in 23 months.

'The US is having a holiday today, and the crude and equities markets are not expected to move dramatically,' said Ken Hasegawa, a commodity derivatives manager at Japan's Newedge brokerage. “The upper side of WTI will be $92.50 a barrel, with the lower side at $90.00 a barrel.' 

The uptrend in the equities market has supported the crude market, he added.

The S&P 500 ended a seventh straight week of gains last Friday with a banks-led rally amid healthy volume after encouraging financial results from JPMorgan.

The strength in financial stocks combat the soft December retail sales and consumer sentiment dented by rising gasoline prices.

The dollar index against a basket of currencies remained dangerously near its December low.

The index stood at 79.10, not far above its Dec. 31 low of 78.775, a break of which could fan expectations for more dollar weakness.

A weaker greenback supports dollar-denominated commodities such as oil, making them cheaper for holders of other currencies.

Opec unlikely to intervene

Iran's oil minister Massoud Mirkazemi said over the weekend that $100 a barrel for oil was a 'real' price, and no Opec countries had requested any emergency meeting to discuss the rising price of crude.

Separately, Secretary General Abdullah al-Badri told an Austrian newspaper that while OPEC was ready to act to address supply shortages in the oil market, it would not intervene if prices were driven by speculation.

At this stage, higher output will not stem the rise in crude oil prices, as the climb is driven by increasing demand in emerging countries, chief executive of French oil major Total  Christophe de Margerie told Reuters ahead of an energy conference in the UAE capital Abu Dhabi on Sunday.

But he also added that oil prices had risen too high too quickly and this would not be well received by consumers. This sentiment was shared by Hasegawa.

'Brent is still trying to test the $100 a barrel level, but no one wants to buy crude at that level. It's too expensive from a fundamental view.Most are waiting for some factors to bring the market down to $85.00 a barrel.”

Speculators increased their net long crude oil futures positions in the week through Jan. 11, the Commodity. Futures Trading Commission (CFTC) said on Friday.

Money managers, the group containing hedge funds and other speculative investors, raised their net long positions to 195,655 from 175,862 positions in the previous week.

Tim Evans at Citi Futures Perspective warned that levels were still elevated, describing the market as 'overbought', especially with prices above $90 a barrel.

In Alaska, the operator of the Trans Alaska Pipeline System, which has been struggling for the past week with a leak in piping at the Prudhoe Bay intake station, said the oil artery would resume normal operations late on Sunday or early Monday. – Reuters