Klaus Masuch from the European Central Bank
Klaus Masuch from the European Central Bank (ECB) walks towards the Finance Ministry for a meeting in Athens on Tuesday. Reuters

Some of Europe's largest banks aren't keeping up with their end of a deal to reduce their too-big-to-fail problems.

Instead of getting smaller they've gotten comfortable enough with their dependence on the European Central Bank (ECB) to provide them with capital that they've increased their assets by €34.4 trillion ($45 trillion) in the year ended July 31, according to the ECB, instead of abiding by a pledge to trim assets by $1.2 trillion in that period.

The cycle of dependence on a central bank that oversees 17 independent banking systems all sharing the same currency has become one of the biggest issues in resolving the euro zone's banking crisis. Key to stabilizing the euro and holding the monetary union together is getting banks to to sell risky assets at depressed prices or even at losses and to lend more money; basically to go back to their roots as smaller and leaner institutions to reduce threats to the global financial system from the too-big-to-fail syndrome of euro zone banks.

But according to analysts, with the ECB there to offer a cushion, some of the biggest banks in Spain, Italy and France -- Banco Santander, S.A. (NYSE:SAN), UniCredit SpA (BIT:UCG) and BNP Paribas SA (EPA:BNP) -- have grown rather than shrunk after the ECB decided in December to offer €489 billion. In February it loaned another €530 billion.

But instead of deleveraging, the banks are leveraging.

"The fact that we haven't got on with (deleveraging), or very slowly, suggests that when the time comes we'll need another ECB injection to roll over the first one, just to keep the balance sheets of Italian banks in business," Simon Maughan, bank analyst for Olivetree Securities Ltd. in London told Bloomberg News.

With the ECB there to possibly open up its wallet once again, banks have not been too keen to shed assets at a loss.

At the same time, governments in the most troubled Eurozone economies, such as in Italy, are hesitant to endure the painful process of letting their own, smaller banks -- the ones that are too big to fail locally but not regionally -- go under.

According to the ECB, the euro zone's financial institutions held €32.2 trillion euros in July, three times the currency zone's gross domestic product in 2011, according to Bloomberg News.