A non-European head of the International Monetary Fund could mean a tougher, more realistic action plan for the euro zone debt crisis, Mexican central bank chief Agustin Carstens said in newspaper interviews on Tuesday.

Carstens is the only declared rival to French Finance Minister Christine Lagarde in her bid for candidacy to lead the global lender.

It would be appropriate to have a non-European because a pair of fresh eyes could see European problems with greater objectivity, Carstens told El Pais in a visit to Spain as part of a tour to campaign for the job.

He said he had more experience and authority than Lagarde in an interview with Expansion newspaper.

Greece, Ireland and Portugal have received international bailouts to combat a debt crisis which threatens to swallow other peripheral euro zone countries. Meanwhile, economists fear Greece's sovereign debt levels are unsustainable.

The resignation of Dominique Strauss-Kahn has led to calls from developing countries to end the traditional European lock on the job.

I think emerging countries have been faithful partners in the international economy in recent years and we should be recognized, Carstens told El Pais.

EU nations are strongly backing Lagarde, arguing a European leader is crucial at a time when the IMF is working with the euro zone to avert the risk of Greece defaulting on its loans and sparking wider financial fall-out.

Mexico's Carstens said the only way to solve the euro zone crisis was to take tough measures, without saying what those measures should be.

There are still bitter pills to be swallowed and the international financial community should give its support, but in my experience there is no alternative to taking those tough measures, he said.

The restructuring of Greek or Irish debt was not a magic bullet, he said, and should be a measure of last resort and as part of a wide-ranging program.