ECB Vice President Victor Constancio said that ECB, which raised interest rate in April by 25 basis points to 1.25% to curb inflation, has not yet decided to embark on further tightening over the coming months through raising interest rate further as debt crisis still persist in the region.

He revealed that the procedures taken by the euro zone to halt debt woes are still not convincing to investors as the bond yields for highly indebted nations in the region remain high. Greece may need to restructure its debt and Portugal is seeking a bailout.

The ECB's rate decision for the month of May, due on Thursday, is expected to show no change in interest rate, where analysts predict the bank to raise the rate again in either June or July.