Bank of Spain published on its website today that Spanish banks' borrowing from the ECB skyrocketed by nearly 50% last month. Domestic banks borrowed 227.6 billion euros in March compared to 152.4 billion euros in February.

Spanish banks tapped 29% of the aggregate long-term loans offered to euro-area lenders, including the three-year long-term refinancing operation loans which were launched by the ECB since last year. Also, they borrowed more than 60% of the loans received by other euro-zone banks, according to the data.

Although Spain's 10-year bond yield retreated today, it may come under pressure once again as the announcement mirrors the high reliance of Spanish banks on the ECB's emergency loans to curetheir ailing fiscal position and pump liquidity.