Blue chip shares struggled for direction as rising fuel and food prices saw inflation jump to the highest rate in almost four years.
Consumer Prices Index inflation lifted to 2.3% in February – up from 1.8% in January, pushing the rate above the Bank of England's 2% target, according to official figures.
The FTSE 100 index edged 5.3 points lower to 7424.5 in afternoon trading, amid trader concerns that the highest inflation rate since September 2013 would slow the UK economy, which is driven by consumer spending.
Spreadex financial analyst Connor Campbell said: "Everyone knew inflation would rise in February – even then, however, last month's jump is alarming".
In the second tier, online gaming website 888 said profit almost doubled in a year as it boosted sports betting and casino revenues.
The business, launched in 1997, said annual pre-tax profit jumped 82% to $59.2m (£47.8m) compared to a year ago, as it also expanded in core UK, Spanish and Italian markets.
The FTSE 250 group was driven by strong performances from its casino betting unit where sales climbed 21% to $279.3m over the period, while sales at its sports betting business jumped 49% to $51.9m. Shares lifted almost 8%, or 18.3p to 252.3p.
The biggest afternoon risers in the FTSE 100 Index were Barclays (+4.7p to 233p), Standard Life (+5.5p to 369.2p), Royal Bank of Scotland (+3.1p to 243p), Bunzl (+30p to 2365p) and Legal & General (+2.8p to 253.5p).
The biggest afternoon fallers in the FTSE 100 Index were Rio Tinto (-57p to 3413p), BHP Billiton (-19p to 1317.5p), Glencore (-4.5p to 340.3p), Sage Group (-8p to 632.5p) and Associated British Foods (-33p to 2626p).
The biggest afternoon risers in the FTSE 250 Index were Hastings Group (+15.1p to 265p), Tullow Oil (+7.3p to 204.8p), Hunting (+17p to 551.5p), Vectura Group (+5p to 162.4p) and CLS Holdings (+43p to 1746p).
The biggest afternoon fallers in the FTSE 250 Index were Berendsen (-55p to 803p), Ferrexpo (-7.6p to 166.7p), AO World (-4.2p to 143.3p), Kaz Minerals (-14.5p to 505.5p) and Allied Minds (-9.7p to 370.3p).