Paris — Escalating trade tensions are eroding global growth prospects with the world economy set for its slowest expansion since the global financial crisis, the OECD warned on Thursday.

In an update to its economic forecasts from May, the Organisation for Economic Co-operation and Development cut its global growth forecast for 2019 to 2.9% from 3.2%.

The prognosis for 2020 was lowered to 3% from 3.4%.

“These would be the weakest annual growth rates since the financial crisis, with downside risks continuing to mount,” said the OECD.

The IMF already lowered its own global forecasts in July in face of the long-running and bruising trade war between the US and China, the world’s number one and two economies respectively.

Growth prospects for almost all of the Group of 20 countries were revised down by the OECD, particularly those exposed to declining global trade and investment.

“Escalating trade policy tensions are taking an increasing toll on confidence and investment, adding to policy uncertainty, weighing on risk sentiment in financial markets, and endangering future growth prospects,” the OECD wrote.

The US economy is now expected to expand by 2.4% in 2019, a downward revision of 0.4 percentage points from the May forecast, and slower than the 2.9% recorded in 2018.

The 2020 forecast was cut by 0.3 percentage points to 2%.

Chinese growth is expected to slow to 6.1% in 2019, a downward revision of 0.1 point, while 2020’s forecast was cut by 0.3 points to 5.7%.

The OECD said “collective effort is urgent to halt the build-up of trade-distorting tariffs and subsidies and to restore a transparent and predictable rules-based system that encourages businesses to invest”.

It revised down its forecast for the 19-country eurozone to 1.1% growth in 2019 and 1% in 2020, whereas previously it had been expecting activity in the single currency area to pick up speed.

Britain’s growth outlook was also lowered as uncertainty over Brexit persists, with the OECD now pencilling in expansion of 1% in 2019 and 0.9% in 2020, compared with 1.4% in 2018.

“A no-deal exit would be costly in the near term, potentially pushing the UK into recession in 2020 and reducing growth in Europe considerably,” the OECD warned.