(Refiles with correct day in first paragraph)
* British share index up 0.4 percent
* Antofagasta, Centrica rise after as updates reassure investors
* Diageo falls on emerging market growth concerns
By Francesco Canepa
LONDON, July 31 (Reuters) - British shares rose on Wednesday, led by miner Antofagasta and utility Centrica after solid earnings updates, with trade light ahead of news from the U.S. Federal Reserve on plans for its stimulus programme.
Antofagasta rose 1.8 percent to be among the top blue-chip risers after the miner's copper production update beat market expectations.
The stock has fallen 37 percent in the past six months as investors reacted to a growth slowdown in the world's largest consumer of metals, China, and in emerging markets in general.
"Antofagasta is a relief rally more than anything," Andrew Bass, a sales trader at Sanlam Securities, said.
Centrica rose 1.6 percent after reporting higher first half earnings in an update analysts at Liberum Securities said was as solid.
The FTSE 100 index of leading shares was up 27.9 points, or 0.4 percent, at 6,598.87 points at 0846 GMT, keeping within the past week's tight 90-point range.
Drinks firm Diageo fell 0.7 percent to 1,968 pence in volume already one third of its full-session average for the past 90 days after a quarterly update.
Traders cited a drop in sales in the Asia Pacific region and caution on Brazil, highlighting concerns about the impact of a slowdown in emerging market growth on European earnings.
"Everyone focuses so much on Asia to fuel growth for drinks company," Joe Rundle, head of trading at ETX Capital, said, adding the results were "not disastrous."
The European earnings season has so far been mixed, with just over half of companies that have reported results meeting or beating estimates, Thomson Reuters Starmine data showed.
The FTSE has struggled to hold on to gains recently, closing well off intra-day high in each of the last seven sessions, pointing to fading appetite from investors.
"I am now selling on the bounces," Ed Woolfitt, head of trading at Galvan, said. "Technically, it feels a correction is brewing up."
He added that the Fed's post-policy meeting announcement late on Wednesday could derail the rally.
The U.S. central bank was expected to provide details about plans to dial back its asset-purchase programme, which has helped fuel a 16 percent rally in the FTSE since September 2012. (Reporting By Francesco Canepa; Editing by John Stonestreet)