The blue-chip index fell 1.1% and was on course for its worst daily performance in three weeks. Life insurers and banks dragged the most, dropping 2% and 1.3%, respectively.
Miners slumped 1.4%, tracking iron-ore prices, while BP and Royal Dutch Shell shed 1.4% each.
The domestically focused mid-cap FTSE 250 index declined 0.5%.
Globally, investors treaded lightly as a resurgence in COVID-19 cases fuelled concerns about slowing global growth amid talk of major economies easing crisis-era stimulus measures.
The European Central Bank’s policy decision, due later in the day, was on the radar for cues on whether the bank would take a step towards reducing its emergency economic support for the bloc.
“The potential taper talk doesn’t necessarily please investors, as the COVID situation remains uncertain and European businesses need the ECB’s support to go through what might be another dark winter,” said Ipek Ozkardeskaya, senior analyst at Swissquote Bank.
“I believe that the divergent opinions at the heart of the ECB won’t let the bank make any sharp move in the close future.”
Domestically, Bank of England governor Andrew Bailey said policymakers were split evenly last month on whether basic conditions for a rate hike were met by the British economy’s recovery.
easyJet fell 9.7% after the British airline said it rejected a takeover offer and would raise $1.7 billion from shareholders to fund its pandemic recovery and expand operations.
Genus slid 9.5% as Peel Hunt downgraded the livestock genetics firm’s stock to “hold” from “buy” after it missed annual profit estimates.
On the other hand, Hays jumped 3% to top the FTSE 250 index after Barclays upgraded the recruitment agency’s stock to “overweight” from “equalweight”.
For a look at all of today’s economic events, check out our economic calendar.
(Reporting by Devik Jain in Bengaluru; Editing by Saumyadeb Chakrabarty and Devika Syamnath)