Sri Lanka, July 6 -- BRICS leaders are set to gather in Rio de Janeiro on Sunday, calling for reform of traditional Western institutions while presenting the bloc as a defender of multilateralism in an increasingly fractured world.

Emerging nations, which represent about half the world's population and 40 percent of global economic output, have united over "serious concerns" about US import tariffs, according to a draft summit statement obtained by AFP on Saturday.

Since coming to office in January, Trump has threatened allies and rivals alike with a slew of punitive duties.

His latest salvo comes in the form of letters informing trading partners of new tariff rates that will soon enter into force.

The draft summit declaration does no...