Leaders of the world's 20 biggest economies endorsed on Saturday a global minimum tax aimed at stopping big business from hiding profits in tax havens, and also agreed to get more Covid vaccines to poorer nations.

Attending their first in-person summit in two years, G20 leaders broadly backed calls to extend debt relief for impoverished countries and pledged to vaccinate 70 percent of the world's population against Covid-19 by mid-2022.

However, with a crucial UN climate conference due to start in just...