UPDATE 2-FTSE 100 reverses course to end lower on Imperial slump

* FTSE 100 down 0.3%, FTSE 250 up 0.1%

* Ex-dividend trading drags down main bourse

* Smith+Nephew, Moneysupermarket.com among notable gainers

* Virus cases in South Korea deter more rapid gains
(Recasts with market reversing course, updates share prices
throughout)

By Shashwat Awasthi and Muvija M

Feb 20 (Reuters) - London's FTSE 100 handed back earlier
gains to record losses on Thursday as a 7.3% fall in tobacco
giant Imperial Brands overshadowed a 10% leap in medical
products maker Smith+Nephew.

The blue-chip index slipped 0.3% as Imperial Brands
tumbled on ex-dividend trading, while most other sectors
also traded in the red with a surge in coronavirus infections in
South Korea stoking fears about a deepening health crisis.

Smith+Nephew hit an all-time high and helped limit
losses on the index after the medical products maker forecast
another year of revenue growth.

The FTSE 250 midcap index ended the day with a 0.1%
rise, led by a 19% surge in price comparison website
Moneysupermarket.com following upbeat outlook and a 7%
jump in engineering firm Spectris after 2019 results.

For the most part, the British indexes have drawn support
this week from stimulus measures from China, which cut its
benchmark lending rate to cushion the impact of the coronavirus
epidemic.

Both indexes are headed for a week of gains.

"Investors are making a number of significant assumptions
that governments and central banks will be able to mitigate the
effects of any disruption in the short and medium term," CMC
Markets analyst Michael Hewson said.

"Time will tell whether that is a safe assumption to make,
however in the absence of anywhere else to put one's money, the
line of least resistance for now appears to be to buy stocks."

Among other notable gainers on the main index were defence
firm BAE Systems and lender Lloyds with gains
of 3% and 1.4%, respectively, after their annual results.

However, the FTSE 100's losses were deepened by 1%-1.7%
falls in GlaxoSmithKline and Unilever, whose
stocks also traded without dividend entitlement.

Small-cap bathroom and kitchen products supplier Norcros
slid 11% after it warned annual profit would miss market
expectations and supply chain disruptions due to the coronavirus
outbreak would likely hit performance.
(Reporting by Shashwat Awasthi in Bengaluru; Editing by Shounak
Dasgupta, Saumyadeb Chakrabarty and Alison Williams)