China reported an increase in the number of deaths from and cases of coronavirus, while the first patient has been diagnosed in London, causing market jitters.
At 16:35 the FTSE 100 was down 1.1% at 7,452.03, with its heavy weighting towards commodity stocks, particularly sensitive to events in China, contributing to the weakness.
Energy firm Centrica has tumbled 15.3% to 71.8p having swung to an annual loss as a cap on tariffs and falling energy prices weighed on performance.
The energy supplier announced a pre-tax loss of £1.1bn, compared with a profit of £575m a year earlier.
Barclays shed 1.7% to 176.3p after the banking group reported a rise in annual profit on slightly higher income but warned that the lower interest rate environment and uncertain macroeconomic backdrop would weigh on returns this year.
For the year ended 31 December 2019, pre-tax profit rose to £6.2bn from £5.7bn as total income rose just 2% to £21.6bn.
Domino's Pizza was buoyed 1.5% to 285p on the news it has conditionally agreed to sell its 71% stake in its Norwegian business to minority shareholders Pizza Holding and EYJA Fjarfestingafelag III EHF.
RELX rallied 1.6% to £20.72 following its full-year results, which revealed revenue increased 5% to £7.9bn and adjusted operating profit climbed 6% in 2019 to £2.5bn, with the company proposing a 9% dividend increase.
Shares in self-storage provider Safestore rallied 1.6% to 823p after chief executive Frederic Vecchioli said it had been a 'pleasing start' to the year in its first quarter trading update, with growth driven by its core markets of the UK and Paris.
Flowtech Fluidpower has climbed 3.5% to 100.4p, despite warning of flat profit growth for 2020 after revenue increased just 1.2% as Brexit uncertainty weighed on performance.
Polar Capital traded 1.8% lower at 540p after announcing it has reached an agreement to acquire from LA-based asset manager First Pacific Advisors its International Value and World Equity team led by Pierre Py and Greg Herr. It plans to establish a joint venture with the team called Phaeacian-Partners.