Global equities fell into the red after US President Donald Trump threatened tariffs on $11bn of European goods.
At close, the FTSE 100 was 0.3% lower at 7,425.
Elsewhere, European equities also struggled with Germany's DAX falling 0.9% to 11,850.
Wall Street was in a gloomy mood as the Dow Jones retreated 0.6% to 26,180 at around 5pm UK time.
Brent crude oil dipped 0.5% to $70.71 per barrel.
Shares in department store Debenhams were suspended pending their cancellation tomorrow as the group entered administration, frustrating attempts by Mike Ashley's Sports Direct to gain control of the group. Shares in Sports Direct gained 1%.
LARGE AND MID CAP RISERS AND FALLERS
Shares in Frankie & Benny's owner Restaurant Group rose 3.3% after Citigroup upgraded its recommendation from 'sell' to 'neutral.'
GlaxoSmithKline said its ViiV Healthcare joint venture with Pfizer had received regulatory approval in the US for a two-drug treatment for HIV. Its shares, however, were little moved.
British brand Ted Baker slipped 2.8% after Jefferies downgraded its recommendation on the stock. Utilities firm Severn Trent also came under pressure as JPMorgan Cazenove moved from 'overweight' to 'neutral'.
SMALL CAP RISERS AND FALLERS
Digital music platform 7digital slumped 68.4% as it said it will need to raise more cash to continue as a going concern in the wake of a decision by European retailer MediaMarktSaturn to cancel a partnership agreement earlier this year.
ReNeuron signed an exclusive licence agreement with Shanghai Fosun Pharmaceutical for the development, manufacture and commercialisation for some of ReNeuron's cell programmes in China. Shares in ReNeuron rallied 28.6% to 220p.
Cake seller Cake Box revealed a strong trading update thanks to rising sales, helping the shares rise 3%.
Advertising business Mission Marketing rallied 12.8% to 72.7p after new business wins boosted annual profits.
Equipment rental group VP fell 14.7% after UK regulators said it was among three companies found to have breached competition law by engaging in cartel conduct.
Online gambling group Stride Gaming tumbled 7.1% as it downgraded its sales guidance, blaming 'fiscal and regulatory changes' implemented in the second half of calendar 2018.
Brewin Dolphin, meanwhile, signed an agreement with Avaloq to replace its core custody and settlement system, at a cost of around £35m. Its shares were down 2.2%.
Fund manager Premier Asset Management shed 2.9%, after it announced that a fall in net inflow levels had limited its annual growth in assets under management to 6.3%.
One Media IP soared 23.1% on news that it had acquired the rights for songs by country music writer Michael Dulaney, for $850k.