There was little corporate news to support the FTSE 100, down 0.1% at 7,548 around midday.
Weakness among miners and housebuilders dragged on performance with Persimmon down 1.8% at £24.24 and Antofagasta reversing 1.3% to 832.2p.
Brent crude oil rose 0.9% to $72 per barrel.
MID AND LARGE CAP RISERS AND FALLERS
Royal Bank of Scotland was broadly unmoved at 240.1p after reporting Katie Murray will become interim chief financial officer at the start of October as the bank searches for a successor to Ewen Stevenson.
SMALL CAP RISERS AND FALLERS
Waste management firm Biffa announced four new acquisitions with the biggest, Weir Waste Services costing £16.2m, expected to boost its recycling and waste treatment operations. Shares in Biffa advanced 3.6% to 243p.
Cruise port operator Global Ports revealed its annual results are expected to hit the upper end of its target range, driven by record sales, helping the stock rise 4.1% to 510p.
Construction group Interserve said the company and its consortium reached financial close on a £105m project for Durham University to build two new college facilities, causing the shares to nudge 1.5% higher to 58p.