Mr Putin said repeatedly that there would be no renationalisation of privatised firms on his watch.

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One option - renationalisation - would reduce Yukos's efficiency, said Zarko Stefanovski, senior oil analyst at Aton brokerage.

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The questions were worded to avoid alienating the gas nationalists but also to avoid a self-defeating and costly renationalisation.

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He said that the antidote to "renationalisation" was the enlargement of the European Union and a deepening of Europe's shared functions.

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Recent polls show 70% now support the RMT call for full renationalisation.

BBC: UK

But demands for more government subsidies to modernise the rail infrastructure in the UK have sparked calls from some politicians for renationalisation.

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Gavin Strang said renationalisation would give railways the priority they deserve.

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It is not clear whether the president's aim is renationalisation: she would find it hard to raise the funds, although her threats have depressed YPF's share price by 14% this year.

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