The International Monetary Fund has forecast that 2018 will be the strongest year for global growth since 2011.

In its new assessment of the World Economic Outlook, the IMF predicts growth this year and next of 3.9%.

However, it warned that performance could be curtailed by trade barriers.

It lists a number of risks that could lead to weaker performance than its main forecast, including what it calls policies that "harm international trade".

The report refers to "waning support for global integration". It says increased trade barriers -- tariffs or other restrictions -- could harm sentiment in financial markets, disrupt global supply chains and slow the spread of new technology.

There are warnings about the risks ahead, lurking dangers that could lead to the global economy falling short of the IMF’s forecasts, in addition to the concerns about trade.

Debt levels -- private and government -- are very high. That could lead to debtors getting into difficulty with repayments as interest rates rise from the post -- financial crisis lows.