By Sudip Kar-Gupta
LONDON (Reuters) - Britain's top share index fell to its lowest closing level in more than three years on Friday, hit by losses in commodity-related stocks as BHP Billiton (L:BLT) suffered a major writedown and oil fell below a key level.
The blue-chip FTSE 100 (FTSE) equity index ended down 1.9 percent at 5,804.10 points - its lowest closing level since late 2012.
The FTSE is some 20 percent below a record high of 7,122.74 points reached last April and 7 percent down since the start of 2016.
Concerns over China, the world's second-biggest economy and biggest consumer of metals, have hit oil and metals prices.
Oil fell below the $30 level on Friday, knocking down shares in BP (L:BP) and Royal Dutch Shell (L:RDSa), while copper prices also slid to their lowest level since May 2009. [MKTS/GLOB]
Mining stocks suffered a further blow after BHP Billiton said it would write down the value of its U.S. shale assets by $7.2 billion due to the bleak outlook for oil prices, increasing concerns it will be forced to cut its dividend for the first time in over 25 years.
BHP Billiton fell 6.4 percent, while Anglo American (L:AAL) slumped 11.5 percent. Glencore (L:GLEN) also fell 6.5 percent.
"This is a commodity-driven fall on the markets. Oil has gone below $30, and that's added to fears. It's very difficult to call the bottom of this market," said Thames Capital Markets' trader Daniel Woodward.
Price comparison site Moneysupermarket (L:MONY), which is in the FTSE 250 mid-cap index (FTMC), plunged 10.7 percent after reporting a bigger-than-expected fourth-quarter contraction in its insurance unit.
However, gold miner Randgold (L:RRS) rose 3.7 percent.
Randgold was the best-performing stock on the FTSE 100 as it benefited from a rise in the price of gold itself, which typically gains in value when there are fears about the global economy, due to gold's status as a safe-haven asset. [GOL/]