The London markets dropped marginally as the pound slid to a six-month low as investors become increasingly fearful of a no-deal Brexit.
The FTSE 100 closed down by 12.80 points at 7,536.47 points at the close of trading.
The index failed to benefit from softness in the pound, as investors and pound traders both appeared cautious over Brexit.
Boris Johnson’s comments that October 31 should be treated as a “real deadline for leaving the EU, come what may”, weighed down sterling against both the euro and dollar.
The pound was down 0.53% at 1.245 versus the US dollar and was down 0.45% at 1.111 against the euro.
The UK indices were also impacted by US concerns over equities ahead of evidence by the Federal Reserve chairman on Wednesday, which saw the Dow Jones open lower on Tuesday.
David Madden, market analyst at CMC Markets UK, said: “Stocks are in the red as traders are less hopeful that the Federal Reserve will adopt a very dovish stance.
“The non-farm payrolls update on Friday prompted dealers to adopt a less dovish prediction for the Fed, and that has led to a move lower in stocks.”
The European markets reacted with similar caution.
The German Dax decreased by 0.85%, while the French Cac fell back by 0.31%.
In stocks, Ocado led the FTSE 100’s top performers after its shares surged as the firm said it is still confident in its growth prospects despite the impact of a fire at one of its warehouses.
The online grocer reported a loss before tax of £142.8 million for the 26 weeks to June 2, marking a significant increase on the £13.6 million loss reported last year.
Shares in the retailer closed up 66p at 1,236.5p.
Elsewhere, sports direct saw shares dip after Mike Ashley’s firm announced it secured majority backing for its £52 million bid to take over retailer Game Digital.
The group said its offer for the video games retailer is now “unconditional” after winning approval from shareholders owning nearly 16% of shares.
Shares in Sports Direct slipped 4.4p to 256.4p on Tuesday.
Housebuilder Bovis Homes saw shares lift slightly after it brushed aside Brexit uncertainty to cheer a “significant” step up in profits as it reported rising sales and prices.
The group said housing completions rose 4% to 1,647 in the six months to June 30, with average private selling prices rising to around £342,000, up from £334,700 a year earlier.
Bovis shares closed higher, up 2p at 1,016p.
Pub group Young’s saw shares slide after it blamed the weather for a dip in sales across its pubs group ahead of the company’s annual shareholder meeting on Tuesday.
Shares in the company fell by 50p to 1,650p.
The price of oil edged higher as the dust settled in the wake of the most recent OPEC meeting, where production cuts were extended by nine months.
The price of a barrel of Brent crude oil rose by 0.61% to 64.3 US dollars.
The biggest risers on the FTSE 100 were Ocado, up 66p at 1,236.5p, Centrica, up 1.04p at 87.76p, Royal bank of Scotland, up 2.4p at 228.2p and Auto Trader, up 5.6p at 558.4p.
The biggest fallers on the FTSE 100 were NMC Health, down 133p at 2,302p, Micro Focus, down 111.5p, Melrose Industries, down 7.75p at 179.1p and Antofagasta, down 33.8p at 848p.