The World Bank has cut its forecast for global growth this year given weakness in the developing world.

The aid agency expects the world economy to expand 2.9 per cent in 2016, down from its June forecast of 3.3 per cent but up from 2.4 per cent in 2015.

Several big developing economies, including Brazil and China, are slowing or shrinking. Their troubles have hurt smaller trading partners, which have also been squeezed by shrunken commodity prices.

The World Bank expects developing countries to grow 4.8 per cent, up from a six-year low of 4.3 per cent in 2015.

The U.S. economy is forecast to grow 2.7 per cent, up from 2.5 per cent in 2015; the eurozone, 1.7 per cent, fastest since 2011. China is expected to slow to 6.7 per cent growth from 6.9 per cent last year.