FUKUOKA--Finance chiefs of the Group of 20 major economies meeting in the Japanese city of Fukuoka are debating how to revise tax systems to ensure big companies pay their fair share and support economies as global growth slows.

U.S. Treasury Secretary Steven Mnuchin said Saturday that tax policies must capture the "digitalization" of business to prevent a "race to the bottom" by countries trying to lure companies by offering unsustainably and unfairly low tax rates as an incentive.

Japanese Finance Minister Taro Aso says there must be "no big losers" due to the reforms, which he says could be the most significant in a century.

In Washington, meanwhile, President Donald Trump tweeted that he will refrain from a 5% tariff on exports from Mexico, citing progress on the migration issue.