By Sara Sjolin, MarketWatch

LONDON (MarketWatch) -- U.K.'s FTSE 100 index rebounded slightly Friday after a survey on the Scottish independence referendum from a closely watched pollster put the pro-union campaign in the lead.

The benchmark index added 0.1% to 6,806.96, after closing down 0.5% on Thursday. On the week, the FTSE finished down by 0.7%.

Scotland update: The polls leading up to the Sept. 18 referendum had earlier this week showed the race between "yes" and "no" was neck to neck, with one survey last weekend actually putting the pro-independence voters in the lead. A new YouGov survey published late Thursday showed the "no" was ahead with 52% of votes, calming nerves that the U.K. could break up and giving a lift to stocks in London on Friday.

Movers: Scotland-exposed stocks advanced, with Royal Bank of Scotland Group PLC (RBS) up 1.1%, Lloyds Banking Group PLC (LYG) rising 0.7% and utility firm SSE PLC higher by 0.3%.

Mining firms ended mixed. Shares of BHP Billiton PLC (BHP) turned fractionally lower, Rio Tinto PLC (RIO) rose less than 0.1% and Fresnillo PLC gave up 0.4%.

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