* FTSE 100 down 1.0 percent
* Miners fall as metals prices retreat on demand fears
* Retailers rally as Next Q1 sales beat forecasts
By Tricia Wright
LONDON, May 4 (Reuters) - Weaker miners drove Britain's top share index lower at midday on Wednesday as metals prices fell on concern about demand, offsetting gains from retailers.
The FTSE 100 index was down 58.91 points, or 1.0 percent, at 6,023.97 at 1135 GMT, having risen 0.2 percent on Tuesday.
"I am quite constructive on the FTSE relative to other markets, especially as sterling is continuing to weaken," said Lex van Dam, hedge fund manager at Hampstead Capital, which has $500 million of assets under management.
"I would want to wait, before buying, until the FTSE is above 6,100 on a closing basis," he said.
The positive sentiment on the FTSE 100 index was echoed by Ed Woolfitt, head of trading at Galvan Research. "We are certainly still bullish. One day on a dip is a bit of profits coming off the table in some areas, a bit of a pause for breath, and the opportunity to buy in and see if we cannot push on."
Miners dropped, tracking copper prices on worries about further tightening in top consumer China whose central bank said it would roll out more measures to fight inflation.
Antofagasta was the top blue-chip faller, off 8.3 percent as the Chilean miner said copper production in the first quarter came in about 29,000 tonnes below initial targets and cut its full-year target for its flagship Los Pelambres mine.
The miner also traded ex-dividend of its interim payout and a 100 cents special dividend.
Barclays, GlaxoSmithKline and Weir Group also fell after going ex-dividend.
ENERGY DRAIN
Energy issues were also weak as oil prices consolidated following falls on Tuesday after industry data showed U.S. crude stocks rose sharply last week.
BP shed 1.3 percent. The company has agreed to pay a $25 million civil penalty and $60 million on enhanced safety measures to settle a federal probe of a pipeline oil spill on Alaska's North Slope in 2006.
Buyers came in for retailers, with Next the top FTSE 100 riser, up 4.3 percent as the fashion chain raised guidance after first-quarter sales beat expectations, up 5.2 percent and boosted by exceptionally warm weather in April.
Analysts said Next's results boded well for sector peers, with Marks & Spencer occupying the second top spot on the blue-chip leader board, up 3.2 percent.
"Next has flagged that the fine weather over Easter was very good news for fashion retailers and we all know that food retailers have had a great time ... (and) M&S has a foot in both camps," said Nick Bubb, retail analyst at Arden Partners.
News was not so upbeat on the economic front, with construction sector activity slowing more than expected last month, according to a survey of purchasing managers by Markit/CIPS.
Traders said this, when viewed alongside manufacturing PMI data for April, which also fell short of expectations on Tuesday, more or less guaranteed the Bank of England would keep interest rates unchanged this week. (Additional reporting by Jon Hopkins; Editing by Dan Lalor)