Virtual currency bitcoin meanwhile dived, falling below $10,000 for the first time in six weeks in what one analyst called a "cryptocalypse" that saw several digital units take a hammering.

London stocks "opened on the back foot following downward trends in the US and Asia, signalling a shift in global sentiment as traders opt to lock in profits following the latest rally," noted Russ Mould, investment director at online stockbroker AJ Bell.

Adding to the gloom, disappointing earnings eclipsed takeover activity in the British capital.

Publisher and conference organiser Informa revealed it was in talks to buy rival UBM to create a giant worth more than £9.0 billion ($12.4 billion, 10.1 billion euros).

The deal is aimed at accelerating growth and slashing costs, the companies said in a statement. But investors were unconvinced, sending Informa shares tumbling more than nine percent.

The FTSE 100 was also punished as poor results from luxury fashion giant Burberry and publisher Pearson sent the two companies' share prices diving by seven and five percent respectively.