Boosting investment was key, the G20 financial leaders agreed.

Financial leaders from the world's 20 biggest economies agreed on Saturday to step up reform efforts to boost disappointingly slow growth, saying reliance on ultra-low interest rates would not be enough to accelerate economic expansion. Monetary policies will continue to support economic activity consistent with central banks' mandates. Improving economic outlook, monetary policy tightening is more likely in some advanced economies.

Boosting investment was key, the G20 financial leaders agreed. Governments will prepare their final investment strategies by November.

Concern about the turbulence that might be caused by a possible Fed rate hike was amplified by investor worries over an economic slowdown in China, the world's second-biggest economy. But they also said they were confident growth would pick up and, as a result, interest rates in "some advanced economies" -- code for the United States -- would have to rise.

The Chinese devaluation as well as the stock market plunge on growth jitters were all part of a difficult path to a more liberal economy, officials said.

Last year, G20 leaders agreed to boost global output over the next five years by 2 percent above what was already expected at the time through coordinated reforms and investment. But they were behind schedule