The United States, Britain and other large, rich nations reached a landmark deal on Saturday to squeeze more money out of multinational companies such as Amazon and Google and reduce their incentive to shift profits to low-tax offshore havens.

Hundreds of billions of dollars could flow into the coffers of governments left cash-strapped by the COVID-19 pandemic after the Group of Seven (G7) advanced economies agreed to back a minimum global corporate tax rate of at least 15%.

Facebook said it expected it would have to pay more tax, in more countries, as a result of the deal, which comes after eight years of talks that gained fresh impetus in recent months after proposals from U.S. President Joe Biden's new administration.

"G7 finance ministers have reached a historic agreement to reform the global tax system to make it fit for the global digital age," British finance minister Rishi Sunak said after chairing a two-day meeting in London...

U.S. Treasury Secretary Janet Yellen said the "significant, unprecedented commitment" would end what she called a race to the bottom on global taxation...

Ministers also agreed to move towards making companies declare their environmental impact in a more standard way so investors can decided more easily whether to fund them...

Current global tax rules date back to the 1920s and struggle with multinational tech giants that sell services remotely and attribute much of their profits to intellectual property held in low-tax jurisdictions...

Key details remain to be negotiated over the coming months. Saturday's agreement says only "the largest and most profitable multinational enterprises" would be affected...

Some campaign groups also condemned what they saw as a lack of ambition. "They are setting the bar so low that companies can just step over it," Oxfam's head of inequality policy, Max Lawson, said...