China's President Xi Jinping has opened a summit of emerging economies in South Africa's main city, Johannesburg, with a warning that the world is facing a choice between cooperation or confrontation.

In a speech aimed largely at the Trump administration in the US, Mr Xi said there could be no winner in any trade war.

He believed the countries taking part in the summit - China, Russia, India, Brazil and South Africa - should be resolute against closed-door protectionism.

The Chinese leader said:

A trade war should be rejected because there will be no winner.

Unilateralism and protectionism are mounting, dealing a severe blow to multilateralism and the multilateral trading regime.

We are facing a choice between cooperation and confrontation, between opening up and closed-door policy and between mutual benefit and a beggar-thy-neighbour approach.

The international community has again reached a new crossroads."

The Brics group - as it is known - comprises more than 40% of the global population.

Analysts say its members have struggled to find a unified voice, but their common opposition to US trade policy could help to galvanise them.