A leading credit ratings agency is warning that a surge in populism and anti-establishment sentiment is pushing the world into an era of economic nationalism to the detriment of long-term global growth.

In its outlook for 2017, Fitch Ratings says increased trade protectionism and weaker migration flows would dampen growth in advanced economies though short-term budgetary measures will likely provide a boost for next year.

Fitch has revised up its global growth forecasts for next year by 0.1 percentage point, largely on the back of a fiscal boost expected in the U.S. following Donald Trump's January inauguration as president.

One downside risk, Fitch says, centers on whether the "populist surge" accentuates tensions in Europe.

Fitch identified Britain's vote to leave the European Union and Trump's election as acts of populism.