Britain's top share index fell sharply on Monday, with all individual stocks in the red and miners leading the slide on growing fears of a China-led global economic slowdown.
Alarm bells rang across world markets after a 9 percent dive in Chinese shares and a sharp drop in the dollar and major commodities panicked investors.
Traders said investors were effectively being forced to sell to raise cash after widespread losses across markets and that the chain reaction had yet to reach its end.
"There is a snowball effect happening, with margin calls putting pressure on positions and creating forced sellers," said Mark Ward, head of execution trading at Sanlam Securities.
"Every order has been a sell today, across the board, so clearly people think we haven't hit the bottom yet."
The blue-chip FTSE 100 was down 2.8 percent by 1054 GMT, reaching its lowest level since early 2013.
The index, which marked its biggest weekly loss of the year on Friday, has now fallen for 10 sessions in a row, its longest continuous decline since 2003.
The mining sector led the fallers, dropping 5 percent to its lowest level since 2009 as fears around China's growth continued to bludgeon commodity prices. Glencore and Anglo American fell more than 6 percent.
Oil stocks Premier Oil and Tullow Oil fell 7 to 10 percent.
Small cap UTV Media was one of the few stocks to outperform, gaining more than 8 percent after saying it was in talks to sell its television assets.