By Carla Mozee, MarketWatch

LONDON (MarketWatch) -- U.K. stocks fell Monday, with the main index unable to withstand renewed pressure from sharply falling crude prices.

The FTSE 100 reversed a 0.4% rise to fall 0.7% to 6,453.48, following Friday's 1.1% drop.

Energy stocks were in the red as crude-oil futures continued to slump following steep cuts by Goldman Sachs of its forecasts for oil. As U.S. trading opened, losses intensified for the commodity, with Brent North Sea crude oil for February down 4.6% to below $48 a barrel, and West Texas Intermediate crude oil for February delivery (CLG5) down more than 4% to just over $46 a barrel.

Major oil companies BP PLC (BP) and Royal Dutch Shell PLC (RDSB) fell 1.8% and 2.5%, respectively. Oil producer Tullow Oil PLC gave up 1.4%, and BG Group PLC (BG) lost nearly 4%.

Meanwhile, shares of home builder Taylor Wimpey PLC fell 1.4%. The company said in its trading update that it enters the new year with a "record" order book that has risen in value by 12%, driven largely from private reservations. The company also said for 2015 is beginning with "a lower rate of price growth" that should foster a more sustainable housing market.

On the upside, engineering group GKN was high on the gainers list, rising 1.8% after Credit Suisse said opportunities from its automotive operations "offer potential to deliver upside surprise" to consensus estimates for a measure of GKN's earnings, particularly in fiscal year 2016. The price target was raised to GBP4.10 ($6.20) from GBP3.80.

Shares of Associated British Foods rose 0.4% as Credit Suisse also pushed up its price target on the parent company of apparel retailer Primark to GBP32.50 from GBP30 ahead of the company's sales update on Thursday.

With Primark sales set to grow and ABF's sugar business "no longer the drag, we see double-digit EPS growth over the medium term," said Credit Suisse analyst Charlie Mills in a note. Earnings may grow about 15% in the 2015/16 year as ABF enters the U.S. market and sugar recovers somewhat. Primark is slated to open its first U.S. store this year in Boston.

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