Britain's FTSE hits 3-week low as miners extend losses

(ADVISORY- Reuters plans to replace intra-day European and UK stock market reports with a Live Markets blog on Eikon - see cpurl://apps.cp./cms/?pageId=livemarkets for site in development. See the bottom of the report for more details)

* Blue (OTC BB: BUES - news) -chip FTSE 100 down 0.5 percent

* Miners come under further pressure

* Sainsbury (Amsterdam: SJ6.AS - news) 's down on poor trading outlook

By Atul Prakash

LONDON, May 4 (Reuters) - Britain's commodity-heavy FTSE 100 index slipped to a three-week low on Wednesday, with basic resources stocks extending the previous session's hefty losses following a further decline in metals prices.

The blue-chip FTSE 100 index dropped for a third straight session and was down 0.6 percent at 6,150.72 points by 0837 GMT after falling to 6,150.37, the lowest level since early April.

The UK mining index fell 3.3 percent after slumping 6.8 percent on Tuesday as copper prices slipped further on lingering concerns about a weakness in global manufacturing activity.

"Miners are pulling back after a strong run of around 50 percent since February lows, with investors realising that the rally was not based on concrete fundamentals. Recent economic numbers have been disappointing, putting pressure on the sector," Jawaid Afsar, senior trader at Securequity, said.

Shares (Berlin: DI6.BE - news) in global diversified miner BHP Billiton (NYSE: BBL - news) , fell 6.3 percent, the top decline in the FTSE 100 index, also after federal prosecutors in Brazil filed a 155 billion-real ($43.5 billion) civil lawsuit against iron miner Samarco and its owners Vale and BHP over the fatal collapse of a dam in November.

"The overnight news of a fresh legal challenge suggests that the March settlement between BHP, its domestic partner Vale and the Brazilian government was just the beginning of the road," Mike van Dulken, head of research at Accendo Markets, said.

"A silver lining at this early stage is the shares holding above January rising support," he said, adding that its share losses were limited by hopes that a smaller figure could ultimately be agreed.

Commodity miner and trader Glencore (Xetra: A1JAGV - news) , which reported a fall in output of copper, zinc, lead, coal and oil following a decision to cut production because of low prices, was down 1.7 percent, while Anglo American (LSE: AAL.L - news) , Antofagasta (Other OTC: ANFGF - news) and Rio Tinto (LSE: RIO.L - news) dropped 1.8 to 3.2 percent.

Retailers were broadly under pressure, with supermarket Sainsbury's falling 5.7 percent after saying it did not expect tough trading conditions to lift any time soon as it reported a second straight year of profit decline.

Tesco (Xetra: 852647 - news) was down 3.1 percent and Marks & Spencer (Other OTC: MAKSF - news) fell 2.5 percent. However, Next (Other OTC: NXGH - news) rose 3.7 percent despite lowering sales guidance as investors took the advantage of its drop to 2-1/2-year low in the previous session.

ADVISORY- Reuters plans to replace intra-day European and UK stock market reports with a Live Markets blog on Eikon (see cpurl://apps.cp./cms/?pageId=livemarkets for site in development). In a real-time, multimedia format from 0600 London time through the 1630 closing bell, it will include the best of our market reporting, Stocks Buzz service, Eikon graphics, Reuters pictures, eye-catching research and market zeitgeist. Breaking news and dramatic market moves will continue to be alerted to all clients and we will continue to provide a short opening story and comprehensive closing reports.

If you have any thoughts, suggestions or feedback on this, please email mike.dolan@thomsonreuters.com.

Mike Dolan, Markets Editor EMEA. (Reporting by Atul Prakash; Editing by Angus MacSwan)