* FTSE 100 falls 0.5 percent; no MPC, Fed surprises
* Banks, energy stocks fall
* Miners, Imperial tobacco gain
By Simon Falush
LONDON, Sept 22 (Reuters) - Weaker banks and energy stocks, weighed by nagging concern about the state of the U.S. economy, helped drag Britain's top shares lower around midday on Wednesday.
By 1052 GMT the FTSE 100 was down 27.48 points or 0.5 percent at 5,548.71 after it fell 0.5 percent on Tuesday.
Banks, which tend to be sensitive to even slight shifts in risk appetite, were the biggest drag on the index, with Lloyds Banking Group off 1.1 percent and HSBC 0.9 percent weaker.
Banks were also weighed down by a statement from German peer Deutsche Bank which hurt bank shares late on Tuesday.
The bank said sales and trading activity during July and August was weaker than a year ago, providing a warning shot that third-quarter investment banking earnings could be weak across the board.
Markets retreated on Tuesday on nervousness ahead of the Fed's statement on monetary policy, published after London's close.
In the event, the U.S. central bank nudged the door wider to pumping more money into the economy but kept overnight interest rates unchanged near zero, as expected.
U.S. stocks initially popped higher after the Fed statement, but gave back those gains quickly and ended flat.
Some investors had hoped that with recent improvements in economic data, the Fed would issue a more upbeat outlook or clarify the measures it would take to stimulate demand.
But in the absence of any positive surprises, investors took the statement as an excuse to sell equities after a 13 percent gain in the FTSE 100 so far in the third quarter.
"We're seeing a bit of nervousness, investors are pulling back after we've seen the best part of 700 point rally in the last four or five months," said Giles Watts, head of equities at City Index.
Minutes of the Bank of England's Monetary Policy Committee meeting on Sept 8-9 showed BoE policymaker Andrew Sentance had repeated his lone call for an interest rate hike while some of his colleagues thought the probability that more monetary easing would be needed had increased.
Energy stocks retreated as fears on the demand outlook weighed on the sector. BP and Royal Dutch Shell fell 1.6 and 0.5 percent respectively.
Miners bucked the trend, however as metal prices firmed with gold hitting a record peak. Randgold Resources and African Barrick Gold both rose around 2.2 percent respectively, while Rio Tinto added 1.8 percent.
TOBACCO GAINER
Imperial Tobacco was the other standout gainer, adding 1.6 percent after it said its key global cigarette brands continued to perform well and announced volumes in line with its expectations.
With the market hemmed in a fairly tight range, investors were also eying technical levels.
"(There is) support around 5,505/10, the lows of the last week or so, while below that there should also be some interest around 5,435 which was the old 61.8 percent retracement level of the down move from the highs to the lows of this year," said Michael Hewson market analyst at CMC Markets.
He added that the index needs to consolidate itself above 5,600 to re-target the 5,800 highs.
Across the Atlantic, after Tuesday's Federal Reserve meeting, investors will have the latest weekly U.S. mortgage and refinancing indexes to assess on Wednesday afternoon, together with the July FHFA Home price index.
Among stocks in retreat, Weir Group fell 3.1 percent after RBS cut its rating on the stock to "hold" from "buy" on valuation grounds.
Ex-dividend factors clipped 1.19 points off the FTSE 100 index on Wednesday, with Aggreko, Aviva, and Petrofac all losing their payout attractions. (Editing by Hans Peters)