Europe should relieve Greece of some of its debt burden as its savings program would only stifle economic growth, the head of the world's biggest bond fund was quoted as saying in a German magazine on Saturday.

Pacific Investment Management Company's (Pimco) chief executive, Mohamed El-Erian, told Der Spiegel that Greece's only way out of its debt crisis was for Europe to reduce Greek debt from 140 percent of gross domestic product (GDP) to 90 percent.

Debts should fall under 90 percent of GDP, said El-Erian, who helps oversee more than $1.1 trillion in investments. The people cannot withstand (the current savings program).

El-Erian said international investors would only return to Greece once the economy was growing sustainably again. Athens could afford to take a time-out from the euro to achieve this, before joining the common currency bloc once again when it was on a more competitive footing, he said.

El-Erian said on Friday he was not yet buying Greek, Irish or Portuguese sovereign debt.

In the magazine interview, El-Erian also warned that the United States' current expansionary fiscal and monetary policies could drive inflation worldwide.

Instead, the U.S. should brace itself for long-term weak growth, high unemployment and a new configuration of the world economy, he said.

(Reporting by Sarah Marsh)