LONDON: London's mid-cap index fell from four-month highs on Tuesday on concerns around the timeline of a Covid-19 vaccine as well as uncertainties over a Brexit trade deal with the European Union ahead of a self-imposed UK deadline.

The domestically focussed FTSE 250, considered a barometer for Brexit sentiment, sank 1.5%, while the blue-chip FTSE 100 slipped 0.5%.

Prime Minister Boris Johnson and the head of the European Commission are set to discuss Brexit negotiations on Wednesday afternoon ahead of the EU summit on Oct. 15, while the German Europe minister said the EU will have to step up preparations for a no-deal possibility.

Sentiment was also hit by news that Johnson & Johnson had paused its Covid-19 vaccine candidate clinical trials due to an unexplained illness in a study participant, delaying a high-profile effort to contain the global pandemic.

Shares of Tesco Plc and WM Morrison Supermarkets Plc closed up more than 1%. In company news, clothing retailer French Connection Group Plc tumbled 19.6% after posting a plunge in first-half sales due to the health crisis.