* FTSE down 1.2 percent
* Banks weak on global economic woes
* Sainsbury knocked by Deutsche Bank downgrade
* Weak copper and crude weighs on commodities
By Simon Falush
LONDON, Sept 5 (Reuters) - Britain's FTSE 100 <
> was set for its biggest weekly fall in over six years on Friday, as jitters about the global economy hit the struggling bank sector, while falling metal and oil prices pulled commodities lower.By 1103 GMT, the UK's blue-chip index was 68.3 points lower at 5,294.0, bringing losses for the week to around 6 percent -- the biggest such fall since July 2002.
Escalating worries about the health of the global economy were compounded on Thursday with two reports on the U.S. labour market, ahead of the closely watched non-farm payrolls report due at 1230 GMT.
"Analysts are expecting a loss of 75,000 jobs. After studying the economic reports we believe that number is too optimistic," said David Evans, market analyst at BetOnMarkets.
"If the employment data comes out soft, watch for the FTSE and all the other major stock exchanges to finish the day deep in the red."
UK banks were the biggest losers by midday, with comments from European Central Bank President Jean-Claude Trichet on Thursday adding to fears about the ability of the financial sector to weather the slowdown.
"Banks are still responding to the negative comments from the ECB and there are nerves about funding going forward," said Keith Bowman, an equity analyst at Hargreaves Lansdown Stockbrokers.
Across the Atlantic, Wall Street suffered its steepest decline in more than two months overnight on signs of weakness in the labour market, while Japan's Nikkei <
> fell almost 3 percent earlier on Friday.Barclays <BARC.L>, Royal Bank of Scotland <RBS.L>, Lloyds TSB <LLOY.L> and HBOS <HBOS.L> shed between 4 and 1.9 percent.
RSA Insurance <RSA.L> was a rare bright spot in the financials sector, gaining 4.8 percent as traders cited bid interest from Allianz <ALVG.DE> [
].
MINERS SLIDE
Miners took a hit from falling copper prices <MCU3=LX>, with Rio Tinto <RIO.L> down 3.4 percent and Eurasian <ENRC.L> down 7.7 percent.
Ukrainian iron ore miner Ferrexpo <FXPO.L> dipped 9 percent and touched a 14-month low as investors worried about the collapse of Ukraine's governing coalition on Wednesday.
Oil stocks were also pressured by falling crude prices <CLc1> with oil down to about $106 a barrel, as flagging U.S. demand and a firm dollar extended crude's losses to 8 percent this week.
Cairn Energy <CNE.L>, Royal Dutch Shell <RDSa.L>, and Tullow Oil <TLW.L> fell between 0.9 and 2.1 percent.
J. Sainsbury <SBRY.L> fell 3.2 percent after Deutsche Bank downgraded its rating to "sell" from "hold".
The broker said: "We believe that the business will be increasingly competitively hampered by a lack of ability to aggressively cut costs without impacting the customer proposition".
Citigroup also made cautious comments on the food retailer's first-half performance and the prospects for it meeting full-year guidance in a sector review on Friday.
On the upside, positive broker comment helped Unilever <ULVR.L> to feature among the small crop of FTSE 100 stocks in the black. The Anglo-Dutch food and household products group was up 0.5 percent after UBS hiked its stance to "neutral" from "sell" following Thursday's appointment of a new chief executive at the firm.
Pharmaceutical stocks, seen as defensive investments that perform relatively well when more risky sectors suffer, were the biggest gainers. GlaxoSmithKline <GSK.L> gained 0.3 percent while AstraZeneca <AZN.L> was 0.2 percent higher. (Additional reporting by Jon Hopkins; Editing by Erica Billingham)