Oil prices eased further below $57 today as top world crude exporter Saudi Arabia said OPEC producers could decide at any time to add more supply to the world market.
A rebound in the dollar - the currency used in global oil trade - also helped to soften prices, countering worries of a possible strike by oil workers in Nigeria next month over employment issues.
US light crude for April delivery fell 32 cents to $56.40 a barrel, more than $1 from an all-time peak at $57.60 struck last Thursday. London Brent was down 24 cents a barrel at $55.35.
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.
The kingdom, along with other OPEC members, 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, with a second tranche to follow at the discretion of OPEC President Sheikh Ahmad al-Fahd al-Sabah of Kuwait.
A rebound in the value of the dollar against other currencies, triggered by speculation that the US Federal Reserve may signal a more aggressive pace of interest rate rises at its meeting tomorrow, also pushed the oil market lower.
Tempering losses today, Nigeria's oil unions said they will stage a three-day strike starting April 11 to protest working conditions. US gasoline futures rose to an all-time high of $1.60 a gallon today on the news.
Gasoline is increasingly becoming the focus of oil markets ahead of the peak-demand summer driving season, which gets under way in May. Nigeria is a favoured source of crude for US refiners.
