* Fear of swine flu pandemic hits sentiment
* Banks retreat after sharp gains on Friday
* Commodity stocks slide on demand fears
* GlaxoSmithKline rises; BA and tour groups fall
By Simon Falush
LONDON, April 27 (Reuters) - Britain's leading share index was down 0.6 percent by late morning on Monday, pressured by banks and commodity stocks as fears of a swine flu pandemic dented sentiment and hurt British Airways <BAY.L> and travel companies.
By 1101 GMT the FTSE 100 <
> was down 24.07 points at 4,131.92 after jumping 3.4 percent on Friday and gaining 1.5 percent last week. The UK index is down 7 percent this year but has rallied 19 percent since hitting a six-year low on March 9.Heavyweight commodity stocks fell sharply as raw material prices fell on demand concerns exacerbated by the swine flu which has already killed 103 people in Mexico.
Oil majors BP <BP.L> and Royal Dutch Shell <RDSa.L> shed 1.2 and 1.5 percent, respectively.
"It's the way markets behave. There's an intensity of over-reaction to events like this," said Howard Wheeldon, strategist at BGC Partners.
Markets came off their lows touched earlier in the session as investors awaited more evidence on the seriousness of the outbreak.
"There's going to be a marking of time until the crisis passes or the newsflow gets worse by the hour," Wheeldon said.
Miners BHP Billiton <BLT.L>, Rio Tinto <RIO.L>, Anglo American <AAL.L>, Xstrata <XTA.L>, Kazakhmys <KAZ.L>, Vedanta Resources <VED.L>, Antofagasta <ANTO.L> fell 1.1-3.5 percent.
The virus from Mexico -- a major exporter of oil, coffee and factory goods -- has spread to the United States and as far as New Zealand. (For more on the swine flu, click on [
])The threat of a global pandemic hit shares in British Airways <BAY.L>, the heaviest blue-chip faller, already reeling from a severe recession, as well as other travel and transportation operators.
British Airways descended 7.9 percent, cruise operator Carnival <CCL.L> dropped 7 percent, Thomas Cook <TCG.L> shed 4.5 percent and TUI Travel <TT.L> sagged 4 percent, while Intercontinental Hotels <IHG.L> slid 4.6 percent.
Rolls-Royce <RR.L>, the aero engine maker, also suffered, losing 4 percent.
"The swine flu seems to be one of those "Black Swan" events that has caught the market by surprise. This is a concern as to whether it might impact any potential ... recovery chances," said Martin Slaney, head of derivatives at GFT Global Markets.
But GlaxoSmithKline <GSK.L> advanced 3.3 percent. Its Relenza, or zanamivir product along with Roche's <ROG.VX> Tamiflu, is the recommended drug for seasonal flu and has been shown to work against viral samples of the new disease. [
]Peers AstraZeneca <AZN.L> and Shire <SHP.L> put on 1.8 and 1.7 percent, respectively.
Banks also weighed on the index, with heavyweight HSBC <HSBA.L>, down 2.8 percent and Standard Chartered <STAN.L> down 3.6 percent, though Royal Bank of Scotland <RBS.L> and Lloyds Banking Group <LLOY.L> added 2.1 and 1.3 percent respectively.
Domestic economic news added to the gloom. House prices in England and Wales fell by 10.1 percent in April compared with a year ago, while prices declined at their slowest monthly pace for a year, property data company Hometrack said.
The number of mortgages approved for purchase in Britain fell by a quarter year-on-year in March the British Bankers Association said.
Meanwhile almost 70 percent of Britain businesses plan to freeze or cut wages this year and half expected to cut jobs or make staff redundant, a survey by the British Chambers of Commerce showed, the Daily Telegraph said.
Defensive utilities performed well, benefiting from a flight to safety in the wake of the swine flu.
Centrica <CNA.L>, United Utilities <UU.L> and National Grid <NG.L> added 2.2-2.9 percent.
Insurer Aviva <AV.L> advanced 2.4 percent after it reported an increase in its capital cushion and said its first quarter sales rose by a better-than-expected 11 percent. (Additional reporting by Dominic Lau; Editing by Greg Mahlich)