By Sara Sjolin and Barbara Kollmeyer, MarketWatch

NEW YORK (MarketWatch) -- The U.K.'s FTSE 100 index moved slightly higher on Wednesday, with investors encouraged by better-than-expected unemployment data, but remaining cautious ahead of the nearing referendum on Scottish independence.

London's benchmark index rose 0.1% to 6,801.28, but still lagged gains for bourses across Europe. The index has been down for two straight sessions, amid investor caution over the potential for a "yes" outcome to the Scottish vote to leave the U.K. Polls open Thursday, with the results expected early Friday. Read: Good riddance, Scotland: We don't need you

In the latest polls, the pro-union camp was still narrowly in the lead, but analysts call the race at this point too close to call. Both sides of the debate were making their final pitches on Wednesday, with Scotland's First Minister Alex Salmond writing to voters and pleading for a "yes" vote.

The pound (GBPUSD), which has been suffering from uncertainty surrounding the referendum, showed some strength, trading at $1.6311, versus $1.6282 late Tuesday.

Unemployment data: It was also a busy day on the U.K. economic calendar, with the latest round of labor market data out. The goods news was that the joblessness rate for the three months to July dropped to a lower-than-expected 6.2%, marking the lowest level since August 2008. The bad news, however, was that wage growth remained low, meaning that Brits continued to suffer from falling pay in real terms.

Bank of England minutes: The central bank was also in the spotlight after releasing its minutes from the September meeting, where the Monetary Policy Committee kept interest rates and the quantitative-easing program unchanged. The vote on interest rates was unchanged at 7-2 in favor of keeping the benchmark lending rate at a record low of 0.5%.

Sam Hill, senior U.K. economist at Berenberg, said in a note that the minutes struck a dovish tone, as the MPC said, "accumulating evidence of the weakness in the euro area had been the most significant development during the month".

The two-day U.S. Federal Open Market Committee meeting could keep investors at bay. The focus will fall on the Federal Reserve policy statement and any change in language that could hint of a sooner-than-expected hike in interest rates. Read: The only two words that will matter at the Fed

Stocks:Smiths Group PLC topped the losers list with a more than 5% drop, after the medical-device and airport-scanner maker posted a fall in full-year revenue and profit, dragged by a weak performance at its detection business.

Miners were on the rise, with heavyweights such as Rio Tinto PLC (RIO) up 1% and BHP Billiton PLC (BHP) adding 0.5%. Anglo American PLC rose 0.4%.

Lloyds Banking Group PLC (LYG) was a heavyweight gainer, up 1.9%, and chip designer ARM Holdings PLC (ARMHY) added 2.4%.

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