The International Monetary Fund has warned that the growing trade war between the US, China and the European Union could significantly harm the global economy.

"The impact that it could have on GDP, which in the worst case scenario under current measures... is in the range of 0.5 per cent of GDP on a global basis," IMF chief Christine Lagarde said at a meeting of G20 finance ministers and central bank governors in Buenos Aires.

The IMF calculated various scenarios emanating from the US' decision to impose tariffs on steel and aluminium, and punitive tariffs in response from China and the EU.

Under the worst scenario of the tariffs shattering investor confidence, worldwide growth in 2020 could be reduced by 0.5 per cent, or approximately $US430 billion less than previously forecast, the IMF determined.

Although all countries would be negatively impacted by the trade war, the US economy would be particularly hard hit as scores of American products could be hit with retaliatory tariffs, IMF experts said.

On Friday, US President Donald Trump suggested he was considering imposing tariffs on all goods imposed from China.

Earlier this month, the US and China each imposed tariffs on $US34 billion worth of goods, with the US later threatening to impose additional tariffs worth $US200 billion.

In June, Trump raised US import duties on steel and aluminium products from the EU, alongside others - a move that prompted the bloc to retaliate by raising tariffs on more than $US3 billion worth of US goods.