Moody's Investors Service kept its growth forecast for the Group of 20 economies at just over 3 percent for this year and next, but warned of geopolitical risks, U.S. protectionism, and spillovers from global monetary tightening and China's deleveraging measures.

The ratings agency said surprisingly strong data in the first half of the year prompted it to raise 2017 growth forecasts for China to 6.8 percent from 6.6 percent, for South Korea to 2.8 percent from 2.5 percent, and for Japan to 1.5 percent from 1.1 percent.

It also expected the euro zone to accelerate in the rest of the year as suggested by robust sentiment indicators, and revised upwards its forecasts for Germany, France and Italy.