World Trade Organization Chief Roberto Azevedo (Photo: AFP)

He said in a statement to the International Monetary Fund's spring meetings that most of the impact of the trade war will hit poor countries the hardest.

Azevedo expressed concern over the possibility of a sequence of unilateral, tit-for-tat measures, all of which generate uncertainties for global trade and GDP growth. He urged countries to use the WTO as a forum for resolving any disputes, which will be essential to prevent current tensions from escalating.