Oil fell below $104 per barrel on Monday as expectations of increased supply offset strong US job growth.
US crude for August delivery was down 25 cents to $103.81 a barrel at 08:20 SA time in electronic trading on the New York Mercantile Exchange.
The contract sunk as low as $103.70 on Friday before closing at $104.06.
Brent crude, a benchmark for international oils, was up 2 cents at $110.66 on the ICE exchange in London.
Crude fell despite signs the US economy is steadily improving, which typically would increase demand.
Employment grew by an unexpectedly large 288,000 workers in June.
Oil has been sliding since it reached a 10-month closing high of $107.26 on June 20 due to concern about an advance by Islamic militants in controlling Iraqi territory.
Since then, it has become clear that there are no imminent disruptions to supplies from Iraq, OPEC's second-biggest producer.
On top of that, an agreement in Libya between the central government and a regional militia was expected to lead to the reopening of two eastern oil terminals that would boost the country's crude exports by about 500,000 barrels a day.
Libya currently produces around 350,000 barrels of oil a day.
In other energy futures trading on the Nymex:
- Wholesale gasoline was down 0.5 cent at $3.015 a gallon.
- Natural gas lost 0.7 cent to $4.332 per 1,000 cubic feet.
- Heating oil fell 0.7 cent to $2.922 a gallon. - Sapa-AP