LONDON: Gloomy quarterly results from banks and a clutch of other firms saw the FTSE 100 post its worst session in five weeks on Thursday, while uncertainty about US elections and a collapse in economic growth in the world's largest economy also weighed.

The blue-chip FTSE 100 ended 2.3% lower on broad-based losses, with Lloyds Banking Group sliding 7.6% to an eight-year low after swinging to a rare pre-tax loss in the first half of 2020.

Standard Chartered tumbled 6.2% as the lender posted a 33% slump in first-half profit after a six-fold jump in credit impairment charges.

The mid-cap FTSE 250 slipped 1.3%, led by a 12% fall for car dealer Inchcape as impairment charges pushed it to losses.

The export-laden FTSE 100 is on track to record monthly declines in July after rallying since April as faltering economic data and surging Covid-19 cases have dented optimism over a swift post-pandemic economic recovery.

Oil majors BP and Royal Dutch Shell lost 3.6% and 5.5% as crude prices fell on fears that more Covid-19 containment measures could hurt demand.

London shares of travel company TUI slipped after it said it will shut 166 stores in the UK and Ireland due to the downturn in travel caused by the coronavirus - a move that will lead to more losses in the battered sector. AstraZeneca, meanwhile, rose 1.6% on an upbeat second quarter and reiteration of 2020 forecasts, while defence company BAE Systems jumped after announcing plans to restart dividend payouts.