The head of bond investor PIMCO says in an interview that heavily indebted Portugal is at risk to follow Greece's downhill path.

German news magazine Der Spiegel quotes Mohamed El-Erian, CEO of the giant bond mutual fund company, as saying that Portugal is likely to need a second bailout package which will cast further doubt on the country's solvency.

El-Erian told Der Spiegel in the interview published Sunday that Portugal will come under increased scrutiny and "financial markets will be nervous because they are worried about a participation of the private sector."

Greece has required a second international multi-billion bailout package and its private creditors took significant losses on their bond holdings to avoid a Greek bankruptcy.