European shares fall back as Ukraine keeps investors on edge

* FTSEurofirst 300 dips 0.4 pct, Euro STOXX 50 down 0.5 pct

* Sanctions against Russia so far seen as 'soft'

* Cairn Energy (LSE: CNE.L - news) sags on loss, halted buy-back programme

By Blaise Robinson

PARIS, March 18 (Reuters) - European stocks fell in early trade on Tuesday, trimming the previous session's gains as tensions in Ukraine following Sunday's referendum in Crimea kept investors on edge.

Shares in truck maker Scania (Other OTC: SVKBY - news) featured among the top losers, falling 3.2 percent after board members responsible for assessing a takeover bid by Volkswagen (Other OTC: VLKAF - news) for the outstanding shares said the offer was too low and recommended that shareholders reject it.

At 0840 GMT, the FTSEurofirst 300 index of top European shares was down 0.4 percent at 1,292.06 points, after gaining 1 percent on Monday.

Russian President Vladimir Putin announced on Tuesday that Russia would move forward with procedures to annex Ukraine's Crimean region, defying Western sanctions.

"We don't know the next stage, but as long as there is continued Western opposition to what has happened, it's difficult to see any near-term conclusion," Ioan Smith, managing director at KCG, said.

On Monday, the United States and the European Union imposed personal sanctions on a small group of officials from Russia and Ukraine accused of involvement in Moscow's violation of Ukraine territory, although the sanctions were seen as modest by investors.

"The sanctions taken against Russia are relatively soft, and there has been no real escalation in the tensions in the past week, which is good news," Talence Gestion fund manager Alexandre Le Drogoff said.

"Overall, the market has been quite resilient in this Ukrainian crisis, but now it needs a positive catalyst to resume its rally, and we might have to wait for first-quarter corporate results for that."

Around Europe, the UK's FTSE 100 index was down 0.4 percent, Germany's DAX index was off 0.8 percent, and France's CAC 40 was 0.4 percent lower.

Oil and gas explorer Cairn Energy plunged 6.8 percent after saying it would halt its share buy-back programme and posted a 2013 loss of $556 million, hurt by costs for unsuccessful exploration in Morocco and the North Sea.

Bucking the trend, German specialty chemicals maker Wacker Chemie rose 0.8 percent as the group said it expects profits and sales to increase this year after it reached a deal to keep on selling polysilicon to solar companies in China, its single most important market.

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