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* FTSE 100 down 0.2 pct
* Miners on the back foot as trade tensions persist
* Anglo American rises on report of possible bid
* Sainsbury's rises after trading update
By Kit Rees
LONDON, July 4 (Reuters) - Britain's top share index fellback on Wednesday, weighed down by fresh weakness among minersand energy stocks, though investors cheered Sainsbury's tradingupdate.
The blue chip FTSE 100 index was down 0.2 percent at7,581.34 points by 0904 GMT, slightly underperforming a flat toweakly-positive European stock market. Mid caps weredown 0.4 percent.
A rise in the pound following better-than-expected UKservice PMI data also weighed on the FTSE's dollar-earningsconstituents.
A fall across materials stocks weighed on the British index,with shares in Rio Tinto, BHP Billiton andAntofagasta trending 0.8 percent to 1.5 percent lower asunderlying metals prices continued to struggle, hit by concernsover trade between the U.S. and China.
Likewise shares in big oil stocks BP and Royal DutchShell declined around 0.2 percent.
Trading more broadly has been choppy as a July 6 deadlinelooms, when the U.S. is set to impose tariffs on $34 billionworth of Chinese goods.
"With just two days to go until the U.S.-Sino trade warthreats start to take effect, relations between the U.S. andChina remain hostile, rattling investors," analysts at LondonCapital Group said in a note.
Among standout gainers, shares in supermarket Sainsbury's, popped 1.1 percent higher after the grocer gave anupdate on trading in its fiscal first quarter.
Though Sainsbury's saw sales growth slow in its latestquarter, the 0.2 percent rise in retail like-for-like sales wasahead of analysts' average forecasts.
"We know that consumers were in fine fettle in May, as theRoyal Wedding and some good weather lifted spirits, and that’shelped Sainsbury’s to achieve a positive period of trading,"Laith Khalaf, senior analyst at Hargreaves Lansdown, said.
Khalaf had a word of caution, however, for a sector whichhas struggled with a rise in inflation and a squeezed consumer.
"Conditions remain challenging though, and while the topline is just about growing, Sainsbury’s efforts to lower pricesmean that may not entirely feed through into profits," addedKhalaf.
Shares in Anglo American were the biggest gainers,up 3.7 percent on the back of a report of a possible bid for theminer's South African business.
Among fallers, shares in Compass Group were down 1.4percent the catering group said that its finance chief wasleaving, the second key executive change at Compass this year.(Reporting by Kit ReesEditing by Matthew Mpoke Bigg)
