Kazakhstan's sovereign-wealth fund, Samruk Kazyna, which also holds a controlling stake in BTA, owns a further 22% in the Turkish lender.

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The suspects' names were put into Europol's database to find out whether they had been to other EU member states, Bulgarian news agency BTA reported.

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BTA's announcement last week that it would revamp its marketing, using a new less-traditional logo which, unlike the current one, is not dominated by the Union Jack.

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The British Tinnitus Association (BTA) said it backed the campaign.

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Ablyazov is former chairman of BTA, the biggest bank in Kazakhstan, which was nationalized last year amid billions of dollars of losses and linked to possible embezzlement issues that Ablyazov has denied.

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