* FTSE off 0.2 pct; Fitch downgrade of Portugal weighs
* Oils fall; crude dips under $81
* Miners retreat as metals prices weaken
* Eyes on budget at 1230 GMT
By Tricia Wright
LONDON, March 24 (Reuters) - Britain's top share index fell on Wednesday, pressured after ratings firm Fitch cut Portugal's debt rating with oil stocks and banks leading the losers before the UK finance minister's annual budget statement.
By 1138 GMT, the FTSE 100 <
> was down 10.14 points, or 0.2 percent, at 5,663.49, falling back from a peak of 5,698.87 earlier in the session. It rose 0.5 percent on Tuesday, hitting a fresh 21-month closing high."That news about Portugal came out and slightly unsettled the markets and knocked everything back," said Mark Priest, senior equities trader at ETX Capital.
Fitch lowered Portugal's rating to AA- from AA, with a negative outlook. [
]In the UK, finance minister Alistair Darling is set to deliver his pre-election buget at 1230 GMT. The Labour government looks set to use the budget to cut its estimates for borrowing as a record budget deficit has spooked investors.
Energy stocks were the biggest laggards, retreating after good gains the previous session, with BG Group <BG.L>, BP <BP.L> and Royal Dutch Shell <RDSa.L> shedding 0.3 to 0.8 percent.
Cairn Energy <CNE.L> dropped 1.1 percent, falling back after Tuesday's share price leap when it accompanied full-year results with upbeat comments on its operations in India and Greenland, with JPMorgan cutting its rating to "neutral" on valuation grounds.
Banks were weaker with HSBC <HSBA.L> and Barclays <BARC.L> off 0.8 and 0.5 percent. However, Lloyds Banking Group <LLOY.L> rose 1.5 percent after BofA Merrill Lynch added it to its Europe 1 List and hiked its price target.
"Everything you read (about the budget) is 'safe and workmanlike' and I can't really believe it's going to be anything other than that," Priest said.
A pullback in metals prices took the shine off miners, which rose strongly on Tuesday, with Antofagasta <ANTO.L> Kazakhmys <KAZ.L> and Lonmin <LMI.L> off 0.6 to 1.5 percent.
Anglo American <AAL.L>, however, added 0.6 percent after JPMorgan upgraded its rating on the firm to "overweight", and after top diamond producer De Beers, 45 percent owned by Anglo, said it has had a strong first quarter with sales five times the level of last year.
Thomas Cook <TCG.L> topped the FTSE 100 <
> leaderboard, putting on 2.8 percent supported by a price target hike from HSBC and by firm results from peer TUI Travel <TT.L>, which shed 0.4 percent.Aviva <AV.L>, BSkyB <BSY.L> and Intercontinental Hotels <IHG.L> fell after trading went ex-dividend. (Editing By Mike Nesbit)