Oil prices slipped on Friday, extending a steep fall from the previous session on surging U.S. output and an expected supply increase from producer club OPEC and putting crude on track for weekly declines.
Brent crude oil futures were at $70.56 per barrel at 0127 GMT, down 19 cents, or 0.3 percent, from their last close.
U.S. West Texas Intermediate (WTI) crude futures were down 7 cents, at $61.74 per barrel.
Both crude futures lost almost 3 percent in value the previous session.
"Oil prices have fallen as the pressure of record U.S. output levels continues to weigh," said Mihir Kapadia, chief executive officer of Sun Global Investments.
U.S. crude oil production reached a record 12.3 million barrels per day (bpd) last week, rising by around 2 million bpd over the past year. U.S. crude exports broke through 3 million bpd for the first time this year, according to data from the Energy Information Administration.
Analysts say U.S. supply will rise further as its export infrastructure is improved.
"One of the things that we can see in the near future is the de-bottlenecking of the Permian basin in the U.S. through new pipelines and export capacity. This will connect the world's largest shale basin to the global oil market," said Will Hobbs, chief investment officer for Barclays Investment Solutions.
Rising U.S. oil production has helped offset some of the disruptions from U.S. sanctions against Iran and Venezuela, and from supply cuts led by the Middle East-dominated producer club of the Organization of the Petroleum Exporting Countries (OPEC), which started in January.
Despite these disruptions and sharp oil price rises in the first months of this year, some analysts say the long-term price risk to crude oil is skewed to the downside.
Erik Norland, senior economist at commodity derivative exchange CME Group, said "the 130 percent rise in U.S. production due to the shale oil revolution" during the past decade had created a strong and constant downside risk to oil prices, which was visible in exchange trading positions.
"Observers of the oil markets might be surprised to discover that during the past decade, out-of-the-money (OTM) put options were more expensive than OTM calls 92.5 percent of the time for crude oil," he said.
"In other words, oil traders have spent much more time during the past decade worried about downside risks than prices heading higher," Norland added.
(The story corrects headline and first paragraph to say that prices are heading for weekly decline, not second week of falls)