* Banks under pressure after RBS H1
* Miners fall; metals prices weaker
* Investors cautious ahead of key U.S. jobs report
By Tricia Wright
LONDON, Aug 7 (Reuters) - Britain's top share index fell in early trade on Friday, dragged lower by banks after Royal Bank of Scotland's glum first-half results, and with investors bracing themselves ahead of the latest U.S. jobs report.
By 0809 GMT, the FTSE 100 was down 46.11 points, or 1 percent, at 4,644.42, having closed 43.40 points higher on Thursday at 4,690.53.
"Obviously (there is) a little bit of nervousness ahead of the jobs report from the market. After a tremendous rally we're certainly entering, at least in the short term, an element of consolidation, but at these sorts of levels," said Henk Potts, a strategist at Barclays Wealth.
The blue-chip index has surged about 34 percent since hitting a six-year trough in March, and is up almost 5 percent for the year.
"We've got to say that we've gone through the second-quarter reporting season in reasonable shape, which in due course will no doubt lead to some upgrades by analysts," Potts said.
State-owned Royal Bank of Scotland was the biggest FTSE 100 faller, off 15 percent after posting a 1 billion pound ($1.7 billion) loss in the first half of the year, hit by 7.5 billion pounds of bad debts. The bank also named a new finance director to boost turnaround efforts.
The headline loss attributable to shareholders compared to a year-ago loss of 827 million pounds.
UK banks have signalled this week the worst was over for bad loans and hinted a recovery could be around corner, but RBS, 70 percent owned by the UK taxpayer, struck a more cautious note, warning its results would be "poor" over the next two years.
Lloyds Banking Group was the second-biggest blue-chip casualty, off 5.4 percent, with Barclays, and HSBC down 1.1 percent and 1.7 percent, respectively.
Mining stocks were under pressure, as copper eased, reflecting a weaker tone across the base metals, as traders took to the sidelines ahead of the key U.S. jobs data.
Anglo American, BHP Billiton, Rio Tinto, Kazakhmys and Xstrata fell between 2.3 and 5.2 percent.
OILS, DEFENSIVES GAIN
Energy stocks added the most points to the blue-chip index, despite oil prices edging down from a six-week high in the previous session.
BG Group, BP and Royal Dutch Shell gained 0.5 to 0.6 percent.
Strength was seen among defensive stocks, as investors turned to assets perceived as safe bets as their appetite for risk waned.
Heavyweight Vodafone added 0.9 percent, while British American Tobacco put on 0.7 percent and AstraZeneca rose 0.9 percent.
Cobham was among the top blue-chip gainers as Citigroup lifted its rating on the aerospace and defence electronics group to "buy" from "hold" in the wake of Thursday's first-half results.
Security services group G4S added 1 percent, tracking Swedish peer Securitas, which rose despite posting below-forecast second-quarter earnings.
Domestic inflationary factors will be under scrutiny early on Friday, with UK July PPI numbers due for release at 0830 GMT.
UK PPI input prices are seen down 0.7 percent month-on-month in July, after a 1.5 percent rise in June, with PPI output numbers seen up 0.1 percent in July after a 0.2 percent decline in the previous month.
Investors will then focus squarely on the U.S. July nonfarm payrolls which are forecast to show a 320,000 decline, after a 467,000 fall in June, with the unemployment rate seen up to 9.6 percent in July, from 9.5 percent in June.
June U.S. consumer credit numbers will also be a focus later in the afternoon. (Editing by Hans Peters)