FTSE tracks commodity weakness, slides 1.1 pct

* FTSE falls 1.1 percent, touches lowest since May 5

* Miners weaker as confidence in demand for metals ebbs

* Pharmaceuticals stocks gain ground; BT top riser * Sainsbury slides after capital raising

By Simon Falush

LONDON, June 17 (Reuters) - Britain's top share index fell 1.1 percent by midday on Wednesday as commodity stocks fell back, dented by a retreat in energy and metal prices and as investor confidence in the state of the global economy waned.

By 1044 GMT the FTSE 100 was down 48.16 points at 4,280.41, touching its lowest since May 5, having closed 2.56 points higher at 4,328.57 in the previous session.

Miners were the biggest drag on the index as metal prices were stuck well below the highs since late last year struck last week as hopes the global economy was set for a sharp rebound faded.

Rio Tinto (RIO.L), Kazakhmys (KAZ.L), Eurasian Natural Resources (ENRC.L), Anglo American (AAL.L), Lonmin (LMI.L) and BHP Billiton (BLT.L) fell 3-7.4 percent.

"We've had an aggressive move to the upside and there's profit taking going on as it looks as though the rally has moved too far too fast," said Henk Potts, strategist at Barclays Wealth.

The blue-chip index is down 3.4 percent for the year but is still 23.7 percent above a six-year trough set on March 9.

"There are still plenty of reasons to be positive given low interest rates and unprecedented levels of stimulus from quantitative easing," Potts added.

"But there are still a lot of unanswered questions and investors will wait for tangible evidence before pushing the market higher."

Energy stocks were also a big drain on the index as crude fell back towards $70 per barrel CLc1.

BP (BP.L), Royal Dutch Shell (RDSa.L), BG Group (BG.L), Tullow Oil (TLW.L) and Cairn Energy (CNE.L) fell between 0.3 and 2.7 percent.

Employment data that showed the jobless rate rose at a slower than expected rate in May did little to cheer investors.