London's top-flight index was dragged into the red as a lacklustre performance from commodity stocks weighed heavy on the market.
The FTSE 100 Index was down 49.5 points to 6260.9 as mining stocks dominated the biggest fallers in the wake of weak commodity prices.
Anglo American led the market down as it failed to bounce back from last week's slump driven by shareholder anger over executive pay at its annual general meeting.
Shares fell 53.7p to 679.1p, while BHP Billiton slipped 57.3p to 930.3p and Glencore dropped 6.8p to 155p.
Oil giant BP finished in negative territory, down 7.9p to 360.4p, as it took a hit from Brent crude's eight-cent slip to 45 US dollars a barrel.
Across Europe, Germany's Dax was down 0.76 and the Cac 40 in France fell 0.52.
The pound was up more than 0.5% to 1.448 - its highest level in more than a month - amid increased confidence that Britain is likely to remain in the European Union after President Barack Obama warned that it could take up to a decade to strike a trade deal with the US if Britain voted for Brexit.
Sterling was also up 0.15% against the euro at 1.285.
In stocks, retailers were on the front foot after the collapse of beleaguered high street department store chain BHS boosted prospects for trade.
The privately owned retailer fell into administration, putting 11,000 jobs at risk and threatening the closure of up to 164 stores.
It is the biggest retail failure since Woolworths went bust in 2008.
Administrators Duff & Phelps said last-ditch talks to find a buyer for the firm over the weekend had failed, adding: "In addition, property sales have not materialised as expected in both number and value."
Shares in Marks & Spencer were up 4.9p to 432.9p, while online retailer ASOS rose 33p to 3717p and boohoo edged ahead 2.5p to 50p.
However, high street bellwether Next saw shares tumble after investors questioned whether the tough trading BHS faced on the high street could trouble other retailers.
Next chief executive Lord Wolfson warned in March that consumers may be shifting spending away from clothing towards other areas, such as eating out and travel.
He said: ''The year ahead may well be the toughest we have faced since 2008.''
Shares in Next were down 10p to 5150p.
Oil giant Royal Dutch Shell slid into the red as it pushed ahead with plans to cut jobs and close offices amid a plunging oil price and its takeover of BG Group.
The cost-cutting drive will trigger three office closures, including the former BG Group headquarters at Thames Valley Park, Reading, BG's offices at Albyn Place, Aberdeen, and Shell's Brabazon House office in Manchester.
It has asked staff at the Thames Valley site to apply for voluntary redundancy, while a separate voluntary severance programme has been rolled out to "some UK employees" as oil prices remain persistently low.
Share fell 61p to 1765.5p.
Global tobacco giant Imperial Brands was the biggest riser on the London market, climbing more than 3%, after Goldman Sachs handed the firm a broker upgrade to buy from neutral.
The biggest risers in the FTSE 100 Index were Imperial Brands up 109.5p to 3681p, Berkeley Group up 85p to 2979p, British Land Company up 18.5p to 703.5p, and Ashtead Group up 24p to 914p.
The biggest fallers were Anglo American down 53.7p to 679.1p, Standard Chartered down 35.6p to 520.6p, BHP Billiton down 57.3p to 930.3p, and Glencore down 6.8p to 155p.