* FTSE 100 up 0.1 pct
* Aviva, Aggreko surge after updates
* Gains pared on fresh Ukraine uncertainty
* BoE likely to keep interest rate unchanged
By Alistair Smout
LONDON, March 6 Britain's top share index edged higher on Thursday, buoyed by updates from as Aviva and Aggreko, although uncertainty over Ukraine capped market gains.
Volumes were also light, with investors wary of making large bets ahead of major central bank policy meetings.
British insurer Aviva rose 9 percent after the company said operating profit rose 6 percent in 2013 and it was proposing a final dividend of 9.4 pence per share. Fund manager Schroders gained 5.7 percent following its higher-than-expected pre-tax profit growth for 2013.
Aggreko, the world's biggest temporary power provider, climbed 8 percent to the top of blue-chip FTSE 100 index after saying it would return 200 million pounds ($334 million) to shareholders.
The FTSE 100 pared stronger earlier gains, however, after the Crimean parliament voted join the Russian Federation, raising the stakes in the most serious East-West confrontation since the end of the Cold War.
The FTSE fell 1.5 percent on Monday after Crimea was effectively seized by Russian forces at the weekend. It more than made up the drop on Tuesday, as Russian President Vladimir Putin played down the prospect of war.
"We bounced too strongly on Tuesday ... and now this vote in favour of Russia sovereignty puts a spanner in the works and delays the resolution of the situation further," said David Madden, an analyst at IG. "The prospect of a war is declining, but the situation is far from over."
At 1104 GMT, the FTSE 100 index was up 0.1 percent to 6,783.63 points, down from an intraday high of 6,806.62.
Trade was light ahead of central bank meetings later in the day, with just 27 percent of the 90 day average volume having been traded.
The Bank of England is likely to keep its interest rates on hold, but the European Central Bank is expected to take action to loosen lending conditions and pull inflation out of a "danger zone".
The prospect of further easing from the ECB helped European shares in general outperform the British blue-chip index.
Technical analysts were unsurprised that the market could make only limited gains, but said that a steady performance was healthy in the medium term and should support a future rise.
"Prices have entered into a consolidation phase but remain supported by the key support threshold at 6640," Nicolas Suiffet, technical analyst at Trading Central, said, identifying the 50 percent retracement level of the February rally as support.
"As long as 6640 holds as a support, a new up leg is likely towards the swing high area around 6865/6875 with 6950 as target in extension."