(Adds futures, company news)
LONDON, March 21 (Reuters) - Britain's FTSE 100 index is set for a slightly lower open on Friday, with futures down 0.1 percent by 0730 GMT ahead of the cash market open. For more on the factors affecting European stocks, please click on
* The UK benchmark closed down 30.69 points, or 0.5 percent, at 6,542.44 points on Thursday. The index's decline leaves it just 2 percent above an early February low, and down 3.1 percent this year.
* Shares of companies with a big exposure to Russia could come under further pressure after Washington extended sanctions and Fitch revised the country's outlook to 'negative'.
Drinks cans maker Rexam, cigarette maker British American Tobacco, and catering firm Compass Group are among UK blue-chips with the biggest exposure to Russia, according to data from index provider MSCI.
For a list of European blue-chips with the biggest exposure to Russia:
* BP : BP has been sucked into the row over Russia's annexation of Crimea with calls for the delisting from the London Stock Exchange of Rosneft, the Moscow-based oil company in which the British group has a 20 percent holding, according to the Guardian.
* BG GROUP : The oil and gas producer is cutting nearly 300 jobs in Britain and making significant cuts in Australia, weeks after warning that turmoil in Egypt would hit output this year and in 2015, the Times newspaper reported.
* ROYAL BANK OF SCOTLAND : A family have won a landmark case giving them the green light to sue RBS for millions over the alleged mis-selling of interest rate swaps that ultimately left them with crippling borrowing costs on a 55 million pound loan, the Independent reported.
* BAE SYSTEMS : Europe's biggest defence contractor on Thursday became the latest British company to enter the debate on Scottish independence.
"It is clear that continued union offers greater certainty and stability for our business," BAE's chief executive Ian King said in the FTSE 100 company's annual report. BAE, which employs 3,600 people in Scotland, called its interests there "significant".
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