The FTSE 100 fell 2.1% to touch its lowest since Dec. 2, though a near 2% plunge in the pound capped losses on the exporter-heavy index.
BP and Royal Dutch Shell were the biggest drags on the index, shedding almost 5% each as crude prices slumped on worries about fuel demand.
British Airways-owner IAG, Wizz Air Holdings and easyJet fell between 11% and 16%, while InterContinental Hotels Group dropped 4% as many of Britain’s European neighbours imposed a ban on travel to the United Kingdom.
The domestically focused FTSE 250, considered a barometer for Brexit sentiment, shed 2.8% with no Brexit trade deal in sight.
Brexit-sensitive banking stocks such as Lloyds and Barclays tumbled over 5%.