Oil stocks struggled as Brent was hit by forecasts for ample supplies in the Atlantic basin and weak demand in Europe and Asia.
Oil prices were also depressed by reports that 30 million barrels of West African crude for lifting in August remained unsold as September cargoes became available.
Gene McGillian of Tradition Energy said the market was now focusing on weak fundamentals.
“If it wasn’t for the geopolitical risk we priced in last week, the market would be at an even lower level,” he said.
On the London market, Shell was 11p lower at 2,407.5p, while BP dropped 2.25p to 496.85p ahead of a scheduled update today.
The driller is just one of many big names reporting this week, and The FTSE 100 Index had a slow day as traders kept their powder dry. It was 3.48 points lower at 6,788.07.
A better-than-expected update from Ryanair eased jitters in the airline sector after the budget carrier raised its guidance for annual profits.
With lower oil prices also favouring the flyers, low-cost rival EasyJet was 1 per cent or 12p higher at 1,344p, but British Airways owner International Airlines Group drifted 1.2p to 337.6p.
BSkyB topped the risers’ board - up 30p to 904.5p - as it recovered from the 5 per cent slump seen on Friday after it announced plans to issue new shares in order to pay for its European expansion.
Among other risers in the top flight, Reckitt Benckiser added 3 per cent after it announced plans to spin off its pharmaceuticals business in a flotation that is likely to raise at least £1 billion.
Shares rose 135p to 5,205p, also reflecting strong half-year results from the household products giant.