Strength in banks and commodity issues hauled the FTSE higher mid-session on Thursday, as euro zone debt concerns eased after Wednesday's hefty ECB loan tender to banks.

By 1145 GMT, the FTSE 100 <.FTSE> index was up 67.13 points, or 1.3 percent at 5,456.37 on the final full-day trading session before the Christmas break, having closed 0.6 percent lower on Wednesday after an afternoon sell-off.

Volumes were low, however, representing around 18.5 percent of the 90-day daily average.

We're up on very thin volumes, so that's exacerbating the movement. I don't think there is any significant buying going on and in the absence of any real positive catalyst I don't think we are going to see much significant buying before the end of the year, said Richard Hunter, market analyst at Hargreaves Lansdown.

None of the themes have changed - the European situation is still moving ahead very slowly. Obviously the ECB loans news yesterday is a mild positive, but in terms of accelerating growth in the euro zone and sorting out the sovereign debt position, that's still a work in progress, Hunter added.

Domestic banks were good gainers, with Royal Bank of Scotland , Lloyds Banking Group , and Barclays up 2.4 to 2.9 percent, extending gains made on Wednesday after the key ECB tender.

European banks took nearly 490 billion euros in three-year cut-price loans from the ECB on Wednesday, easing credit crunch worries and fears over the health of financial institutions.

Insurers also saw strong support on hopes that the euro zone debt situation could be eased by the injection of liquidity from the ECB, with Old Mutual up 2.5 percent.

And fund manager Schroders also rallied, helped by the recovery in equity prices, adding 2.9 percent.

Commodity issues were the top blue chip sector performer as investors' risk appetite improved, with integrated oils standing out, led by BP up 2.8 percent, as crude prices moved higher.

Among individual gainers, International Consolidated Airlines Group (IAG) added 2.5 percent after it signed a deal to buy bmi from Germany's Deutsche Lufthansa for 172.5 million pounds in cash.

Rival Virgin Atlantic , which also made a play for bmi, said it would seek a regulatory block on the deal.

There were only a handful of FTSE 100 fallers, with hedge-fund manager Man Group the worst off, down 1.0 percent.

Investors paid little attention to news of a surprise increase in the final reading for British third-quarter GDP, which was up 0.6 percent on the quarter from a provisional figure of 0.5 percent growth, although the annualised number was unchanged at up 0.5 percent.

Any nascent optimism generated by this was quickly demolished by a downward revision to the second quarter's figure, which was cut from the Scrooge-like 0.1 percent growth to no growth at all, said Chris Beauchamp, Market Analyst at IG Index.

Across the Atlantic, the final reading for third-quarter U.S. GDP is also due on Thursday, together with the November Chicago Fed index, and the latest weekly U.S. jobless claims, all scheduled for 1330 GMT, and the December final Reuters/Univ. of Michigan consumer sentiment survey, out at 1455 GMT.

Ahead of all that data, U.S. stock index futures all pointed to a higher open on Wall Street on Thursday, after a late rally in the previous session took both the Dow Jones and S&P 500 indexes into positive territory.

(Reporting by Jon Hopkins; Editing by Helen Massy-Beresford)