London's FTSE 100 index was down by 2.6% in morning trade, while major markets in France and Germany lost nearly 3%.
Shares in Asia were hit overnight, with the Shanghai Composite in China closing down 8.5%, its worst close since 2007.
The Chinese authorities tried in vain to reassure investors.
In addition, oil prices have plunged to six-year lows, as traders worry about slowing growth in the world's second-largest economy. » | Monday, August 24, 2015