Lower commodity prices hit the mining sector hard, with Glencore (GLEN) leading the descent, down 3.8% to 341p.
Peers Anglo American (AAL) and Rio Tinto (RIO) cheapened 3.1% and 2.4% to £14.10 and £35.05, respectively.
In response, the FTSE traded 0.5% lower at 7,373 around midday.
Brent crude slid 1.1% to $61.52 per barrel. Gold was flat at $1,281 and copper was down 0.7% at $3.04 per pound.
Lower oil prices dragged on shares in energy companies overnight, leaving Wall Street in the red. The S&P 500 closed 0.2% lower at 2,578.
MID AND LARGE CAP RISERS AND FALLERS
Broadband provider TalkTalk (TALK) shed 8.7% to 173p on a pre-tax loss of £75m in the six months to 30 September, down from £30m profit last year as the cost of new customers hit profit.
High street bank HSBC (HSBA) agreed to pay €300m to French authorities as a settlement for an investigation into tax evasion by French clients.
Pharma giant AstraZeneca (AZN) advanced 0.5% to £49.86 after the US Food and Drug Administration approved a treatment for asthma.
Hungarian airline Wizz Air (WIZZ) sealed an early stage deal with Airbus to buy 146 Airbus A320neo family aircraft, but this failed to stop the shares drifting 0.3% lower to £31.54.
Housebuilder Barratt Developments (BDEV) revealed sales rates this year were flat so far, causing the stock to stumble 0.9% to 623p.
In the same sector, Crest Nicholson (CRST) was down 9.2% to 471.3p following a warning that sales in Central London suffered from volumes and price weakness in the year to 31 October.
Credit score provider Experian (EXPN) was stable at £16 despite a 5% increase in revenue and operating earnings in the first half of its financial year.
Greetings card retailer Card Factory (CARD) reported a 6.7% rise in sales in the nine months to 31 October, helping the share price gain 3.8% to 289.3p.
An in line trading update at British aerospace and defence business Cobham (COB) prompted a relief rally of 2.5% to 130.2p.
SMALL CAP RISERS AND FALLERS
Cakes manufacturer Premier Foods (PFD) fattened 7.5% to 39.2p thanks to a 1.5% rise in sales in the half year to 30 September. The strong results helped the group return to a profit of £0.3m.
Interior furnishing group Walter Greenbank (WGB) was the biggest small cap faller, crashing 27% to 153.5p as brand sales in the UK, excluding Clarke & Clarke, weakened significantly.
Specialist engineer Fenner (FENR) reported encouraging results as a 14% jump in sales boosted its operating loss from a £14.7m to a profit of £53.4m in the year to 31 August.
Losses at video games seller Game Digital (GMD) continued to rack up, rising to £10m in the year to 29 July as challenging markets impacted performance. Shares in the firm retreated 2.8% to 39p on optimistic commentary concerning early trading ahead of the peak Christmas period.
Avon Rubber (AVON) announced adjusted operating profit, earnings and net cash beat expectations. Shares in the engineering group were marked 4% higher to £11.08.
Robotic automation software business Blue Prism (PRSM) hiked full year revenue guidance, but investors were concerned with losses, currently at £7.4m. The stock fell 5.7% to £12.60.