* Miners, oils fall as commodity prices hit by firmer dollar
* Banks gain; RBS top FTSE 100 riser after FY results
* Tobacco stocks out of favour; BAT results fail to excite
By Tricia Wright
LONDON, Feb 25 (Reuters) - Britain's top share index slipped in midday trade Thursday, with miners and energy stocks hurt by weaker commodity prices, which outweighed rises elsewhere, including Royal Bank of Scotland <RBS.L> which was up after its full-year results.
By 1202 GMT the FTSE 100 <
> was off 9.08 points, or 0.2 percent, at 5,333.84 after it rose 0.5 percent on Wednesday."It's (been) a sort of morning in which we're not getting any real impetus from anywhere," said Peter Dixon, economist at Commerzbank.
"If RBS is the top riser I think that tells you a lot about what kind of a day it is, because they weren't particularly great results at all irrespective of how they came in versus expectations," he said.
Miners were the biggest drag on the index as metal prices fell with a weaker dollar. Xstrata <XTA.L>, Randgold Resources <RRS.L> and Rio Tinto <RIO.L> were the worst off, shedding 1.9 to 2.7 percent.
Energy stocks were also on the back foot as the crude <CLc1> price fell too. Cairn Energy <CNE.L>, BP <BP.L> and Royal Dutch Shell <RDSa.L> dropped 0.4 to 2 percent.
The dollar rose against the euro, which was pressured again after Standard and Poor's said on Wednesday it may cut Greece's BBB+ debt rating by one or two notches within a month. [
]Investors also had a mixed batch of results to digest on Thursday.
Capita <CPI.L> was among the biggest FTSE 100 fallers, down 2.6 percent after the outsourcing firm's full-year results disappointed slightly, with Seymour Pierce highlighting fears over the organic growth rate at the group.
British American Tobacco's <BATS.L> shares shed 1.9 percent as the world's second-biggest cigarette maker's full-year results met forecasts but failed to excite.
Peer Imperial Tobacco <IMT.L> dropped 0.5 percent.
RBS IN FAVOUR
RBS rose 6.7 percent after its 2009 operating loss shrank to 6.2 billion pounds ($9.51 billion), despite a jump in bad debts, with analysts citing relief that there were no nasty surprises.
The sector as a whole added strength to the blue chips after RBS's numbers. Lloyds Banking Group <LLOY.L>, scheduled to post its results on Friday, added 3.6 percent, while Barclays <BARC.L>, HSBC <HSBA.L> and Standard Chartered <STAN.L> rose 0.4 to 0.9 percent.
Inmarsat <ISA.L> was another big riser, up 3.3 percent, with traders citing lingering talk that U.S. Harbinger Capital is interested in buying up the satellite operator.
Traders also cite a proposal from the U.S. Federal Communications Commission which would free up capacity for wireless telecoms carriers as being supportive of the stock.
Positive broker sentiment lifted Shire <SHP.L>, up 1.8 percent, with BofA Merrill Lynch raising its price target.
Centrica <CNA.L> gained 2.5 percent after the gas distributor reported better than expected full-year results, with EPS of 21.7 pence 6 percent ahead of Goldman Sachs' forecast.
"We're looking for the next big theme which could be dividends," Dixon said. "It could be much more selective investments on the part of investors because it looks from a macro perspective as though we've just run out of gas for a while."
Looking at the health of the UK economy, employers' organisation the CBI's distributive trades data was due to be released at 1245 GMT.