London's FTSE 100 Index added another 118 points to its slide from last week after investors were again rattled by the falling price of oil.

Trading was subdued for much of the session until a drop in Brent crude to below 62 US dollars a barrel triggered fresh selling in commodity stocks.

The FTSE 100 Index, which had been in positive territory earlier in the day, finished 1.9% or 117.9 points lower at 6182.7 following the abrupt turnaround.

The slump comes after £112 billion was wiped from the value of blue-chip shares during the London market's worst week in more than three years, driven by the tumbling price of oil and jitters over the global economy. The top flight is now 8% lower in the month to date.

Among the heavyweight fallers, BP was down 12.4p to 373.25p, Royal Dutch Shell dipped 42.5p to 1989p and BHP Billiton dropped 49p to 1276p.

The US dollar provided refuge for investors as the pound dipped 0.5% against the greenback to 1.56 and also fell against the euro to 1.25.

Banking stocks were under pressure ahead of Tuesday's announcement from the Bank of England on the results of tests showing how the UK's major lenders would cope with severe economic stress. Barclays fell 7.1p to 225.2p and Royal Bank of Scotland dropped 11.9p to 363.7p.

Many retailers survived the sell-off after profit upgrades from Carpetright and Greggs suggested that consumer confidence remained strong.

B&Q owner Kingfisher benefited from the Carpetright statement as its shares rose 4.7p to 319.6p, while Dixons Carphone was up 4p to 425.6p ahead of its own half-year results later this week.

Building supplies firm Wolseley, which owns Plumb Center, was only marginally lower with a fall of 19p to 3516p and Homebase owner Home Retail Group lifted 1.3p to 189p in the FTSE 250 Index.

Shares in Carpetright jumped 14% or 45p to 358.25p after it said half-year underlying profits more than doubled to £6.7 million, leaving it on course for an annual figure at the top end of City forecasts.

The share price rally offered an early boost to new chief executive Wilf Walsh as he set out his plans for revitalising the retail chain.

He vowed to broaden the appeal of the floor coverings business after admitting it was seen as too value focused.

Meanwhile, shares in bakery chain Greggs were 5% higher, up 36p to 692.5p, as it raised City expectations after seeing like-for-like sales rise 5.2% in the 24 weeks to December 13.

It is the second such upgrade in three months as the company benefits from new ranges and favourable weather conditions. The stock is up more than 60% this year.

The biggest FTSE 100 risers were Kingfisher up 4.7p at 319.6p, Dixons ahead 4p at 425.6p, Sainsbury's up 1.8p at 229.3p and Burberry ahead 11p at 1594p.

The biggest fallers were Sky down 39.5p at 863p, BHP Billiton off 49p at 1276p, Anglo American down 37.5p at 1098.5p and BP off 12.4p at 373.25p.