Renewed fears over Ukraine and a slowing Chinese economy sent the FTSE 100 Index to a one-month low as it suffered its fourth straight session in the red.
Falls in Chinese copper and iron ore prices have impacted on mining stocks in recent days as demand fears grow on the back of recently published weak export figures and in the wake of China's first corporate bond default.
While some miners staged a bounceback, it was not enough to offset general investors' concerns, with Sunday's referendum on the future of Crimea also drawing closer - leaving the FTSE 100 Index 64.6 points lower at 6620.9.
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America's Dow Jones Industrial Average followed the lead of European markets, falling more than 30 points in early session trading. There was little movement for the pound in a quiet day for economic news, with sterling remaining at 1.66 US dollars and 1.19 euros.
Security giant G4S led declines in the top tier - slumping 5% or 12.9p to 232.5p - after it reported a £170 million full-year loss in the wake of a major hit from the cost of settling a scandal in which it overcharged taxpayers for the electronic tagging of offenders.
The company took £386m of one-off costs in the year, including in relation to the repayment of £108.9m to reimburse the Government on the tagging contract.
Chief executive Ashley Almanza said it had been an extremely challenging year, but that the company had taken action to address long-standing issues.
Insurer Prudential topped the risers board after operating profits rose 17% to £2.95 billion and it announced a new 15-year deal with Standard Chartered to extend the pair's life assurance partnership.
The improvement in earnings was better than expected and with the Pru also upbeat about prospects this year, shares rallied 3% or 37p to 1398p.
In contrast, Standard Chartered dropped 46p to 1203p, a fall of 4%, after its shares went ex-dividend - meaning new shareholders are no longer entitled to the latest payout.
The same factor meant fund supermarket Hargreaves Lansdown fell 46p to 1339p and banking giant HSBC dropped 17.4p to 599.2p.
The City also welcomed two new stocks to the market, with the start of conditional dealings in Pets at Home and Poundland.
Discount retailer Poundland made strong progress after its shares rose 23% to 370p, giving it a market value of more than £920 million.
However, Pets at Home endured a mixed start after being valued at £1.2bn with a starting price of 245p a share. The stock slipped as low as 225p before clawing back some losses to stand 3% lower at 238p.
The other biggest FTSE 100 risers were Fresnillo ahead 18p at 900p, Antofagasta 13.5p higher at 853.5p and Vodafone 3.3p stronger at 229.6p.