The FTSE 100 was down 0.3 percent by 0835 GMT, extending early losses after strong employment figures sent sterling higher.

The currency had strengthened ahead of Wednesday's EU summit at which some traders remain hopeful of a breakthrough in Brexit negotiations.

Workers in Britain are seeing the fastest pay growth in nearly a decade, figures from the Office for National Statistics showed, boosting the currency further and weighing on the FTSE 100 dominated by dollar-earning international stocks.

Diageo and Unilever were among the top weights on the FTSE 100.

British American Tobacco, the second-biggest international tobacco company by revenue, fell 1.4 percent after it cut its full-year revenue target for cigarette alternatives to 900 million pounds from 1 billion pounds.

The fall, although small, weighed heavily on the FTSE 100 as BAT is among its biggest constituents by market cap.

BAT's statement again sparked uncertainties around a shift to heated tobacco products and e-cigarettes as companies try to maintain revenue growth as cigarette consumption falls.

Heavyweight oil majors Shell and BP were the biggest drag on the FTSE, down 1 percent each, as crude prices dipped amid expectations of an increase in US inventories.

Online grocer Ocado shares topped the FTSE 100 with a 3.2 percent gain after BAML analysts double upgraded the stock to "buy" from "underperform".

Shares in rival supermarket Tesco, meanwhile, fell 3.3 percent after Kantar Worldpanel data showed it lost market share in the 12 weeks to Oct 7 as consumers shopped at discount supermarkets Aldi and Lidl instead.

Overall analysts were sharply downgrading FTSE 100 earnings estimates as the results season began in earnest.

"The earnings season will be vitally important to UK indices given the nervous sentiment around the Brexit outcome and health of the broader European growth story," said Edward Park, investment director at Brooks Macdonald.

Mid-caps saw the biggest moves as earnings flowed in, though the FTSE 250 managed a 0.5 percent rise overall.

Merlin Entertainments shares fell 7.8 percent after it said Legoland's performance over the summer failed to meet its expectations, and warned of cost pressures from labour and regulation.

"The company is holding guidance but the shape changes with lackluster Legoland performance and increased cost inflation, partially offset by better than expected Resort Theme Park trading," wrote Liberum analysts.

JD Sports shares fell 5.1 percent, the second biggest decline on the FTSE 250, after Morgan Stanley started rating the stock with an "underweight" recommendation, saying JD's recent acquisition of US sportswear retailer Finish Line "may be a step too far".

Bellway shares rose only 0.5 percent after it launched a cost savings plan in order to boost margins, also reporting a more than 14 percent rise in full-year profit.

The homebuilder, among Britain's top 5 by market value, said it was mindful that Britain's forthcoming exit from the European Union could hit consumer confidence in the busy spring selling season and also of rising pressures on building costs.