A group of 136 countries on Friday set a minimum global tax rate of 15% for big companies and sought to make it harder for them to avoid taxation in a landmark deal that US President Joe Biden said levelled the playing field.

The deal aims to end a four-decade-long "race to the bottom" by setting a floor for countries that have sought to attract investment and jobs by taxing multinational companies lightly, effectively allowing them to shop around for low tax rates.