The FTSE fell in early trading, dragged down by negative market sentiment towards resources firms.
The index was down 1.3% at 5209.8 points in the first 45 minutes' trading.
Tullow Oil fell by 4.2% to £11.65, as it announced a share placement equivalent to 10% of its existing share base, while miner Xstrata dropped by 4.2% to £10.38.
Cooper miner Kazakhmys fell, by 2.6% to £12.41, on reports of China tightening control over its banks, which fuelled fears copper demand from the country could fall.
The main gainer was chemicals producer Johnson Matthey, which rose by 0.1% to £15.09 after it forecast full year results would be "slightly ahead of current market consensus".
Accountancy software group Sage Group also gained after chief executive Paul Walker said fourth quarter sales had held up; and insurance buyout group Resolution was up by 0.2% to 79.8p.
Overnight in the US, the Dow Jones All Industrials index fell by 2.6% to 10,194.29 points, brought down by fears of China tightening the reins on its banks.
Bank JP Morgan Chase fell furthest in the US, by 2.0% to $38.44.
In Japan, the Nikkei 225 index also fell by 73.2 points to 10,252.1, partly in response to fears over China, and also to news yesterday from ratings agency Standard & Poor's foreshadowing a downgrade of the country.
Carmaker Toyota fell by 4.3% after suspending the sales of some of its models in the US.
