German central bank chief Jens Weidmann has urged the eurozone to impose broad conditions on Spain for its vast banking sector loan, in an interview published in Spanish newspaper El Pais.

The call is a direct challenge to the Spanish government.

Prime Minister Mariano Rajoy insists that the June 9 deal for up to 100 billion euros ($126bn) to save stricken banks imposes no new conditions outside of the financial sector itself.

But "because of the interconnectedness of the different policy areas, I think that the conditionality should be broad," Wiedmann said.

"The impression that this is a rescue with no conditionality outside the financial system is already eroding the commitment to the terms of the existing programmes," he added.