* FTSE 100 down 0.8 percent
* Brent pares gains, but above $115
* Banks fall; Moody's downgrades Spain's rating
* Miners pressured by weak China data
By Tricia Wright
LONDON, March 10 (Reuters) - Britain's top share index fell on Thursday after a downgrade of Spain's credit rating by Moody's hurt risk appetite already waning on concern over the impact of a high oil price on the global recovery.
By 0922 GMT, the FTSE 100 was down 46.55 points, or 0.8 percent, at 5,890.75, having shed 37.46 points, or 0.6 percent on Wednesday.
Brent crude pared some gains, but was trading above $115 on Thursday, after forces loyal to Libyan leader Muammar Gaddafi bombed oil industry infrastructure, inflicting what could be longer-term damage on the country's exporting capacity.
Miners were pressured as copper prices fell after weak Chinese import data cast doubt on demand from the world's biggest consumer of the metal, adding to worries about high oil prices hurting the global economy.
Rio Tinto shed 2.6 percent as it raised its offer for Africa-focused coal miner Riversdale Mining slightly to $3.9 billion in a final bid to woo key shareholders.
"The Spanish downgrade heightens worries especially in light of the ECB's apparent hawkish stance on interest rates which would add more pressure to Southern Europe," Mic Mills, head of electronic trading at ETX Capital, said.
"This, alongside continued Libyan unrest fuelling oil prices, is feeding the negativity surrounding equity markets today."
BANKS KNOCKED
Banks made a dent in London's blue chip index, led down by a 1.9 percent drop in Barclays, which has a big exposure to Iberian debt.
Moody's cut Spain's sovereign credit rating by a notch to Aa2 and warned of further cuts, saying that the country's plans to clean up the battered banking sector will cost more than government expects and add to its debt burden.
Portugal fell under the spotlight on Wednesday, as concerns the country will need to request an international bailout grew. While it successfully sold two-year bonds, the cost of borrowing was the most expensive since it joined the euro.
"Obviously a ratching up of difficulties in Libya with an oil installation being impacted overnight has added to nerves and that comes against a backdrop of a downgrade for Spain by Moody's," Keith Bowman, an analyst at Hargreaves Lansdown, said.
"Add those two together and you've got a rather nervous investor this morning."
Buyers came in for drugmakers, with GlaxoSmithKline the star FTSE 100 performer, up 1.3 percent, after U.S. regulators approve Benlysta, the first new treatment for lupus in 56 years and a potential $3 billion-a-year seller by 2015.
The widely expected green light for the drug, which was discovered by GSK's partner Human Genome Sciences, underpins hopes for the British group's new product pipeline.
Peer Shire gained 0.7 percent, with traders citing the impact of an upgrade in rating by Morgan Stanley.
Aggreko fell 5.7 percent, with the temporary power provider cautious on its 2011 outlook, as it reported a higher 2010 profit, slightly above estimates.
British interest rates are likely to be a focus on Thursday, with the latest Bank of England monetary policy decision due at 1200 GMT. (Editing by Jon Loades-Carter)