Markets across Europe fell again after closely watched industry surveys for the month disappointed traders.
Flash PMI figures for the economies of France and Germany showed slowing growth, while growth figures for the UK stagnated at a 15-month low.
Property and commodities stocks were among the losers in London amid concerns over the global economic outlook.
The FTSE 100 ended the day down 68.77 points, or 0.97%, at 7,020.45.
The German Dax fell 1.76% at the end of the session, while the French Cac fell 0.56%.
“After yesterday’s falls, European markets already looked vulnerable to growing concerns about a global slowdown,” commented Michael Hewson, chief market analyst at CMC Markets UK.
“These fears were further heightened after the latest flash PMI indices from Germany and France highlighted further economic weakness in June, raising fears that both economies could slide into recession.
“The Dax was hit the hardest after the German government triggered the second phase of its emergency gas plan amid fears the economy could face an energy shortage due to fears Russia could cut power. gas supply as the winter months approach.
In the US, major markets started the day in positive territory despite a relatively lackluster set of manufacturing and services PMI numbers for June.
Meanwhile, the pound fell slightly as waning business optimism in the latest PMI report impacted sentiment.
The pound was down 0.1% against the dollar at 1.226 and was flat against the euro at 1.166.
In corporate news, gaming giant 888 lost value after warning half-year revenue set to plummet due to UK’s crackdown on online gambling and its temporary exit from the Netherlands .
The group – which will soon complete its £2.1bn takeover of the UK and European businesses of William Hill – said first-half sales are expected to fall to between £330m and £335m.
The company’s shares fell 14.6p to 160.7p as a result.
Naked Wines lost more than two-fifths of its value on Thursday after the online wine retailer warned of sales and profits for the year ahead.
The group has warned that sales could fall by up to 4% on the year to the end of next March, when it expects to break even only on the basis of underlying profits.
The shares ended the session down 125.3p to 162.1p.
Trainline actions have been derailed as UK rail strikes continued for a second day with little sign of resolution and concerns are growing that strike action could continue beyond this week.
The company fell 32.1p to 284.6p as its chief financial officer also left for online retailer Boohoo.
The price of oil struggled as weak PMI numbers stoked fears that industry demand could weaken due to an economic slowdown.
Brent fell 0.51% to $111.17 a barrel as London markets closed.
The biggest risers in the FTSE 100 were Ocado, up 35.6p at 855.4p, Hikma, up 44p at 1,546.5p, BT Group, up 3.6p at 185.15p, London Stock Exchange Group, up 126p to 7,464p, and Burberry, up 27.5p to 1,633p.
The biggest falls in the index were Antofagasta, down 72.5p to 1,171.5p, British Land, down 27.9p to 477.5p, Rolls-Royce, down 4.26p to 81 .85p, WPP, down 38.2p to 783.2p, and Pershing Square, down 115p to 2,360p.