The true test for the G20 will be whether it can prevent a future financial crisis, World Bank Group President Robert Zoellick said Friday ahead of the upcoming G20 summit in Cannes.

"The world economy is hobbled not only by large deficits and troubled banks, but by joblessness and slow growth," Zoellick noted in an article carried on the website of the Washington Post Friday.

At the G20 summit to be held in France this coming week, the euro zone will present its new plan to recapitalize and strengthen European Union banks, using its new European Financial Stability Facility to enable Italy and Spain to roll over government debts, while assisting Greece, Portugal and Ireland, and easing the debt load on Greece to give it a chance of recovery, he added.

"Developing countries' economic growth has helped compensate for the lackluster performance of developed nations, but they are hardly immune to the shocks coming out of industrialized countries, " Zoellick noted.

He warned that all nations must at least agree "not to do dumb things" which includes a retreat to protectionism or trade wars.

The G20 also must help offset the damage to the poorest countries, which do not sit at the G20 table, Zoellick urged.