Banking shares have been falling across Europe as savers continue to withdraw money from the troubled British bank Northern Rock.
Banks in the eurozone get access to cash from the ECB
The firm's boss told the Independent newspaper that three unnamed Spanish banks had sought help from the European Central Bank (ECB).
Although the ECB denied any Spanish banks had used emergency financing facilities, their shares were hit.
French and Italian banks were also hit on fears of financial woes spreading.
Banks in the eurozone are entitled to use the ECB's routine liquidity facilities, but the ECB stresses that using that does not suggest they are in difficulties.
No other bank matched the falls in Northern Rock shares, which plunged 35% by the end of trading in London.
But Spanish banks fell quite sharply, with Bankinter down 5.1% in late afternoon trading, making it one of the biggest fallers on Madrid's Ibex index.
In late afternoon trading in Paris, BNP Paribas was down 2.4% while Societe Generale had fallen 2.3%.
In Frankfurt, Deutsche Bank shares were down 2.1%.