Finance officials from the G20 group of world economic powers expressed concern Friday about the risks of market and exchange rate volatility but avoided talk of Greece's financial plight.

Meeting in Washington during the IMF-World Bank spring gathering, G20 central bankers and finance ministers said the apparent strengthening in advanced economies "could support a stronger global recovery."

But they warned the economy is still vulnerable to "important challenges" including exchange rate volatility, stubborn low inflation, high public debt and geopolitical tensions.

But the group avoided any official mention of the biggest risk to financial stability at the moment, the risk that Greece could default on hundreds of millions of dollars worth of debt and drop out of the eurozone.

"This was not discussed during the official sessions of the G20," said Ali Babacan, the Turkish deputy prime minister and current G20 president.

Fresh fears that Greece will not secure more bailout funding from the European Union before huge loan payments come due in have sent European equity markets falling again Friday.

While the group avoided Greece, it did say that countries need to do more to boost growth for the near term, and that major central banks need to communicate clearly their policies not to add to market turmoil.

Babacan though said that the US Federal Reserve, whose plan for raising interest rates this year has sent shivers through global finances, is doing "a much better job" of communicating its intentions.

"Clear communication is very important not just for the US economy but globally because of the possible spillover effect," he said.

The G20, meanwhile, said it wanted the IMF executive board to continue efforts to implement the 2010 package of quota and funding reforms, despite the the continued lack of official ratification from the United States, the Fund's largest shareholder.

The G20 said the IMF should seek alternate, interim measures to implement the 2010 reforms, to give large emerging economies like China and India greater voice at the Fund, rather than start a new process.

The refusal of the US Congress to ratify the reform package has angered other IMF members and warnings that Washington is eroding the fund's effectiveness and credibility.