"It is Spain's decision alone whether and how much it needs aid on top of (the banking rescue) from the ESM. I have made that clear in all talks with the Spanish prime minister again and again," Merkel told Germany's Bundestag lower house.

"The conditions for applying for aid are set by the guidelines of the ESM," she said.

Officials have told Reuters that Germany had been urging Spain to hold off making a further request.

Merkel also said she had detected a strong desire to change within Greece when she visited Athens last week and reiterated that she wanted Greece to remain in the euro zone.

"Many states have been implementing hard reforms and adjustment programmes to tackle their specific problems... This is also true of Greece. I was able to see this for myself in Greece during my visit last week," she said.