Oil prices have slipped back from record levels, narrowly avoiding a breach of the $50 a barrel mark.
Traders don't know whether to laugh or cry
Fresh violence in Iraq triggered yet another oil price surge on Friday, before dealers starting taking profits.
New York light crude rose as high as $49.40 after reports of a new attack on an Iraqi oil pipeline, but then slipped back to close at $47.86.
However, with the situation in Iraq still uncertain, oil prices could still surge through past $50, dealers said.
Earlier, Purnomo Yusgiantoro, the president of oil cartel Opec, told reporters he was concerned about the rising oil price.
He added, however, that the group would wait until its next meeting, scheduled for September, before taking action.
"I am concerned to see oil prices continuing to increase. But at the moment, we have not seen cost-pushed inflation," he said.
The UK benchmark, Brent crude oil, recorded a fresh high of $45.15 a barrel, before falling back to close at $43.54 on Friday.
However, this could be a brief respite.
"Oil at $70 is entirely conceivable," for example if "there is a big supply problem and Iraq and Venezuelan oil came off the market", said Bruce Evers, an oil expert with Investec.
The overnight price surge was triggered by news that Shia militants loyal to radical cleric Moqtada Sadr had broken into the South Oil Company's headquarters.
According to witnesses, the Iraqi oil company's warehouses and offices were set on fire.
Markets were also jolted by reports of an attack on a local oil pipeline in Northern Iraq.
Despite slipping back, oil is still trading near its highest level in the 21-year history of crude oil futures on the New York Mercantile Exchange(Nymex).
New records have now been set in 14 out of the last 15 trading sessions on the Nymex.
US futures - the price of oil for deliver in three months' time - have risen by almost 30% since the end of June.
However, when adjusted for inflation, oil prices remain well below the all-time high they reached in the wake of the Islamic revolution in Iran in 1979.
Then, a barrel of crude was worth about $80 in today's terms.
The latest price rise reflected fears that escalating violence would disrupt oil supplies from Iraq, which controls the world's second-biggest proven reserves after Saudi Arabia.
Most analysts predict that prices are set to keep rising, denting world economic growth as companies and consumers struggle with higher fuel and raw material costs.
The main factor behind the surge in prices is soaring world demand, triggered by accelerating growth in the US, and China's economic boom.
According to recent figures, Chinese crude oil imports rose 40% in the first seven months of 2004 compared with the same period last year.
The jump in demand has left oil producing nations operating close to full capacity.
At the same time, the Iraqi conflict and a recent spate of terrorist attacks in Saudi Arabia has sparked fears that supplies from the Middle East, the world's biggest oil-exporting region, could be disrupted.
Iraqi insurgents and Islamic militants in Saudi Arabia have both launched attacks on oil facilities in recent months.
A long-running tax dispute between the Russian government and oil giant Yukos, responsible for 2% of global output, has also underpinned oil prices.
Yukos has warned that asset seizures by the authorities may force it to suspend production.
Earlier this week, worries that Venezuela's output might be disrupted by strikes in the wake of a referendum on whether to keep Hugo Chavez as president further unnerved the oil market.