Updated at 1650 GMT

By Pranav Kashyap and Nikhil Sharma

Nov 5 (Reuters) -Britain's benchmark FTSE 100 edged lower on Tuesday, hurt by AstraZeneca's fall on a potential China probe, while investors remained cautious as U.S. Election Day arrived.

The FTSE 100 .FTSE closed down 0.1% at 8,172.39 points, while the mid-cap FTSE 250 .FTMC fell 0.45% to 20,370.04 points

AstraZeneca AZN.L fell 8.4%, its biggest one-day drop since March 2020, following a report that dozens of senior executives at its China unit could be implicated in the largest insurance fraud case in the country's pharma sector in years.

On the flip side, Melrose Industries' MRON.L shares rose 5.1%, the best performer on the blue-chip index, after Citi raised the aerospace components supplier's free cash flow (FCF) forecast.

American voters headed to the polls on Tuesday to choose between Democrat Kamala Harris and Republican Donald Trump as the next U.S. president. The two were virtually tied in opinion polls, and the winner might not be known for days after voting ends. The outcome will likely be decided by a handful of so-called battleground states.

"A clear winner within the next day would be the ideal outcome here, while a long, drawn-out legal challenge is likely to keep bullish sentiment in check," said Chris Beauchamp, chief market analyst at online trading platform IG.

Following the high-stakes U.S. election, UK investors will shift focus to the Bank of England's policy meeting on Thursday, with traders pricing in a 25 basis-point rate cut.

A survey showed Britain's services sector lost some momentum in October, with business activity growing at the weakest rate in 11 months.

Among other stocks, Schroders SDR.L slumped about 14%, falling to the bottom of the FTSE 100, after the fund manager reported worse-than-expected outflows in the third quarter.

Associated British Foods ABF.L rose 3.2% after the Primark owner said it was well set up for medium-term growth, as it reported a 32% rise in full-year profit.

TP ICAP TCAPI.L gained 7% after the inter-dealer broker reported a 10% increase in its third-quarter revenue.

Reporting by Pranav Kashyap and Nikhil Sharma in Bengaluru
Editing by Tasim Zahid and Matthew Lewis

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