The world's leading economic powers should think about going back to a modified gold standard, according to World Bank Group President Robert B. Zoellick.

He writes in The Financial Times that the world needs a new way to value one currency against another. Zoellick believes that the system should include the dollar, the euro, the yen, the yuan, and gold.

The world banker calls for a system that "is likely to need to involve the dollar, the euro, the yen, the pound and a renminbi that moves towards internationalisation and then an open capital account."

"The system should also consider employing gold as an international reference point of market expectations about inflation, deflation and future currency values," Zoellick added.

Many countries now use gold as an alternative currency. Also, many investors are concerned by the Federal Reserve's plan to help the U.S. economy by printing more money. That move could make the dollar weaker internationally.