The death toll in two separate attacks on the Kenyan coast overnight has risen to 29, according to the interior ministry.
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The German bomb - a 500kg device - was spotted by a barge carrying out dredging works, the Royal Navy said.
The study found children born in the 1980s have found it much harder to build up wealth in housing and pensions as they age.
The singer ended speculation over who would perform by saying "the rumors are true" to her 63 million Twitter followers on Friday morning.