Through a John Doe summons issued to the U.S. bank holding the correspondent account, the IRS can view records of deposits and payments by check and wire.

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Although Wegelin had no branches outside Switzerland, it accessed U.S. banking through a correspondent UBS account in Connecticut.

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Ms Sanchez's Twitter account has not been updated since Thursday and the BBC's correspondent in Havana, Sarah Rainsford, said her mobile phone was unreachable and appeared to have been cut-off.

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Just before the U.S. Federal Reserve raised interest rates by half a point May 16, Biggs and Senior Correspondent Assif Shameen ran through the outlook for various Asian markets, having already taken the hike into account.

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However, the BBC's entertainment correspondent, Lizo Mzimba said that once final figures - which include digital catch-up services - are taken in account, the situation could change.

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