[tialaramex]

The UK's National Savings & Investment Bank, which is owned by the government, offers almost exactly this, your money is guaranteed because it's the government (in taking your "savings" they are in effect borrowing your cash to run the country) so they can and will literally print money to pay you if necessary, however NS&I is intended to be used by individuals, not organisations, maximum balances even in their lower interest generic savings account top out at £2M.