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* FTSE 100 down 0.5 pct
* TUI falls after results disappoint
* Cineworld gets H1 boost from blockbusters
* No-deal Brexit fears sink sterling(For a live blog on European stocks, type LIVE/ in an Eikonnews window)
By Helen Reid and Danilo Masoni
LONDON, Aug 9 (Reuters) - Britain's top share index fell onThursday as several heavyweight stocks went ex-dividend, whiledisappointing earnings sent travel operator TUI down sharply.
The FTSE 100 fell 0.5 percent, recovering partlyfrom bigger morning falls when fresh U.S. sanctions oncommodities giant Russia dampened sentiment.
Washington said on Wednesday it would impose fresh sanctionson Russia by the end of August, after determining that Moscowhad used a nerve agent against former Russian spy Sergei Skripaland his daughter in Salisbury, England.
Oil majors BP and Shell and miner Rio Tinto, who traded ex-dividend, fell 2.1, 1.7 percent, and 1.8percent, respectively.
Elsewhere, earnings continued to drive the day.
TUI shares fell as much as 9.7 percent after itsquarterly results disappointed investors. The tourism groupblamed a summer heatwave for keeping Europeans at home insteadof traveling.
Profitability in the tour operator segment fell, driven byweaker performance in the UK.
"The GBP devaluation and weather impact has been wellflagged, but commentary regarding a shortening of averageduration of holidays is new," said Barclays analysts.
Its shares recovered during the session to end down 2.5percent.
Shares in defence company G4S fell 7.8 percent,suffering its biggest one-day fall since March 2016, afterfirst-half earnings missed company-compiled expectations, partlydue to weaker margins in its Cash Solutions business.
"Attack-related higher operating costs in Africa (followingseveral attacks on cash-in-transit vehicles in South Africa) andinvestment in business development weighed on profitability,"said Goldman Sachs analysts.
Also on the mid-cap FTSE 250 index, card retailerCard Factory fell 10.8 percent after becoming thelatest UK retailer to report fewer customers visiting itsstores.
"The main culprit seems to have been lower high streetfootfall as a result of weather and World Cup," said UBSanalysts.
Cinema company Cineworld topped the FTSE 250 with a10.7 percent gain after it reported a rise in half-year revenuethanks to big-ticket superhero movie releases.Overall, earnings have helped the FTSE 100, with analystsraising their estimates during the season.The FTSE 100 has remained resilient to mounting fears the UKmay be heading for a no-deal Brexit, driving sterling to itslowest against the dollar and euro in almost a year. FTSE 100constituents mostly benefit from a weaker currency.
"If the hard Brexit becomes more of a reality, there mightbe an effect, but at the moment most people think it's a bit ofa Mexican standoff," said Paul Mumford, portfolio manager atCavendish Asset Management.
Stocks going ex-dividend, including Barclays, BT, BP, RoyalDutch Shell, Rio Tinto, and Standard Chartered, took 39 pointsoff the FTSE 100.
(Reporting by Helen Reid, editing by Larry King and HughLawson)
