Spain announced in June that its banking sector, hit hard by a collapsed real estate bubble, needed a bailout. Up to €100 billion in money has been made available by the other members of the 17-country group that uses the euro, but has yet to be disbursed.
The increase from May was more than €8 billion, the second biggest monthly increase on record.
Spain is in its second recession in three years and the jobless rate is almost 25 percent. Many think it will end up requesting a full-blown sovereign bailout because of the government's soaring borrowing costs.