The European Central Bank (ECB) has reported receiving record cash deposits of 412bn euros (£344bn; $539bn).
The heavy usage of the ECB's overnight deposit facility over Christmas suggests Europe's banks remain nervous about lending the money to each other.
The total beat the previous record of 384bn euros set in June 2010.
It comes only a week after the ECB gave banks 489bn euros of three-year loans to try to ward off a fresh banking crisis.
That move - as well as a significant broadening of the types of collateral that the ECB would accept from the banks as security for its loans announced earlier this month - had appeared to settle financial markets in the run-up to Christmas.
Prior to the ECB's interventions, there had been growing fears in the international financial community that a major European bank was about to run out of money and go bust, threatening to spark a full-blown market meltdown.
The ECB has in effect had to fill the role of a safe intermediary in the market for short-term cash loans between the banks - which is crucial to their functioning - by receiving their spare cash as deposits, and then lending it back out to those banks that find themselves short of ready money.
There had also been speculation - including from the French government - that banks would invest a large chunk of the proceeds from the three-year loans in medium-term eurozone government debt.
The European Central Bank is the central bank responsible for monetary policy in the eurozone. It is headquartered in Frankfurt and has a mandate to ensure price stability - which is interpreted as an inflation rate of no more than 2% per year.
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The banks pay approximately 0.75% interest on the loans, whereas the interest rates available on southern European government three-year debts are much higher - 3.6% for Spain, 5.7% for Italy - thanks to fears about the governments' creditworthiness.
Instead, banks appear to be choosing - at least for the time being - to keep their cash in the safety of deposits at the central bank, despite the fact that the ECB only pays a punitively low 0.25% annualised interest rate on the cash.
Southern European governments have large debt repayments falling due in the coming months - much of which they will need to reborrow from markets.
Italy - southern Europe's biggest and most worrying borrower - must meet some 161bn euros of debt repayments between February and April, and is expected to look to its own banks for much of the money.
The country's 10-year implied cost of borrowing in financial markets rose to about 7.1% from 7% on Tuesday - a level widely seen as unsustainable if Rome is actually forced to reborrow money at that interest rate.
Meanwhile, other data from the ECB in recent weeks has suggested that cash has been piling up in German bank accounts in the latter half of this year, while banks in other eurozone countries - notably Greece and other southern European nations - have found themselves short of ready money.
Earlier this month, the head of the Greek central bank, Georgios Provopoulos, said that a run on the Greek banks accelerated during the autumn, as many Greek depositors feared a failure of their bank or an exit from the eurozone, or were simply being forced to run down their savings by the country's recession.