Net debt to the ECB totalled €241.1 billion ($326.3 billion) in September, a 36-percent drop from the level 12 months ago, the Bank of Spain said, a sign that Spanish banks were finding it easier to raise funds on the debt market.
It was the lowest amount since March 2012 when Spanish banks owed the ECB €227.6 billion, and well below the peak of €388.7 billion owed in August 2012, but double the €118.9 billion owed at the end of 2011.
Spanish banks were almost shut out of international debt markets last year owing to concern that the country may need a sovereign bailout and concerns over their balance sheets, which are loaded with piles of bad loans following the collapse of a property bubble in 2008.
But Spanish bank borrowing from the ECB has fallen steadily since the central bank chief Mario Draghi vowed last year to buy sovereign debt of euro zone countries that had requested aid.
Madrid secured a rescue loan in June 2012 of up to €100 billion from its eurozone partners to underpin Spanish banks.
Spain, the euro zone's fourth-biggest economy, has so far withdrawn €41.3 billion from the eurozone rescue loan.
The government estimates the Spanish economy emerged this quarter and will post growth of 0.7 percent next year while the jobless rate will remain high at 26.6 percent.
Prime Minister Mariano Rajoy, whose conservative government has imposed an austerity regime to fix the state's accounts, expects the public debt this year to rise to the equivalent of 94.2 percent of total economic output and to 98.9 percent next year.