Leading shares across Europe have fallen sharply in morning trading amid fears that a renewed rise in coronavirus cases will blight economic prospects.
In London, the benchmark FTSE 100 share index was down more than 3%, with airlines, travel firms, hotel groups and pubs leading the rout.
Worst hit was British Airways owner IAG, which slumped more than 12%.
Similar falls were seen on markets in Paris, Frankfurt and Madrid.
Banking shares were affected by an extra set of concerns as allegations of money-laundering surfaced in leaked secret files.
HSBC, the bank at the centre of the scandal, saw its share price fall more than 5% in London, but the revelations dragged down the entire sector, with Barclays, Lloyds and NatWest all dropping about 6%.
The downward trend affected all but a handful of stocks on the UK's 100-share index. Only online delivery service Just Eat, supermarkets Tesco and Ocado and miner Fresnillo made it into positive territory.
The FTSE 250 index, seen as a better reflection of the health of the UK economy, also declined more than 3%.
Its biggest faller was pub and restaurant owner Mitchells & Butlers, which dropped more than 13% as concerns grow that the hospitality industry would have most to lose from a fresh lockdown.
The pound also lost ground against the dollar, falling 0.58% to $1.2848. It fell marginally against the euro to €1.0902.
'Bitter pill'
Coronavirus cases have been surging in many European countries, as governments strive to avoid another round of national lockdowns.
In the UK, top scientists are warning that the country is at a "critical point" in the pandemic and "heading in the wrong direction".
Prime Minister Boris Johnson is understood to be considering a two-week mini-lockdown in England - being referred to as a "circuit-breaker" - in an effort to stem widespread growth of the virus.
Susannah Streeter, senior investment and markets analyst at Hargreaves Lansdown, said: ''The FTSE 100 is worst hit among its European peers with a storm of pessimistic news swirling, affecting sectors across the board."
She added that concerns for the travel industry had had a "domino effect", with aircraft engine manufacturer Rolls Royce hit, as investors saw no end to the falling demand for new planes.
At the same time, the prospect of evening coronavirus curfews, after a summer of recovering sales, was "a bitter pill to swallow" for the hospitality industry,
If you add the prospect of a no-deal Brexit into the murky mix, there is little surprise so many investors seem to have caught a severe case of the jitters today.''