UK shares were lower on Wednesday as investors returned from New Year celebrations to more disappointing data from China that deepened concerns about the health of the global economy and sparked a global sell-off.
London's blue-chip bourse dropped 0.9 percent and the mid-cap index dipped 0.3 percent by 1018 GMT.
Most sectors were still in the red, setting a bleak tone for 2019's first trading day after both indexes recorded their worst yearly drop since the 2008 financial crisis last year.
Positive domestic PMI data due to Brexit-induced stockpiling provided some respite, but investors were focused on Chinese data that showed manufacturing activity in the world's second-largest economy contracted for the first time in 19 months.
It followed a poor official survey on factory output on Monday. Data also revealed that euro zone manufacturing activity barely expanded in December.
Continued concerns that the prospect of a global cyclical downturn will likely cap the upside of UK's blue-chip shares, said CMC Markets analyst Margaret Yang.
"A string of missing PMIs from China's official and private sector suggest that Asia's largest economy is still cooling off due to weaker external demand and trade uncertainties," Yang added.
"It is still too early to say markets have bottomed out yet."
UK-listed companies with more exposure to the Asian market were the most hit with HSBC edging 1.8 percent lower and Standard Chartered down 3 percent.
Fellow financial heavyweights Prudential, Lloyds and Royal Bank of Scotland also fell over 3 percent.
Global miners were also weak with copper prices lower amid concerns over growth in top metals consumer China. Antofagasta , BHP, Anglo American, Rio Tinto and Glencore were down between 3.2 percent and 4.3 percent.
Blue-chip medical products maker Smith & Nephew tumbled 2.5 percent, with traders citing a rating cut by brokerage JPMorgan.
Among the midcaps, Energean Oil & Gas added 5.1 percent to top the gainers after signing a gas supply agreement with independent power producer I.P.M. Beer Tuvia.
Elsewhere in corporate news, Ophir Energy shares outperformed the small-cap index and soared over 33 percent after the oil and gas producer said it was in takeover talks.
Gambling software company Playtech gave up losses to turn positive. It said it would pay 28 million euros under a settlement with Israeli tax authorities following an audit of its annual accounts.
Real estate investment trust Hammerson was 3.9 percent lower as it said its share buyback program will be paused ahead of the release of 2018 results.