Leaders of the BRICS bloc of emerging economies, meeting in the wake of tariff threats by US President Donald Trump, signed a declaration supporting an open and inclusive multilateral trading system under World Trade Organisation rules at their summit in South Africa on Thursday.
Brazil, Russia, India, China and South Africa agreed at the three-day meeting to fight unilateralism and protectionism.
"We reaffirm the centrality of the rules-based, transparent, non-discriminatory, open and inclusive multilateral trading system, as embodied in the World Trade Organisation, that promotes a predictable trade environment and the centrality of the WTO," the declaration signed by the five leaders said.
The leaders said: "We recognise that the multilateral trading system is facing unprecedented challenges. We underscore the importance of an open world economy."
They called on all WTO members to abide by WTO rules.
The meeting of BRICS leaders is the first since the US administration launched a push to rebalance trade multilateralism that Trump has deemed unfair - relationships that the United States once championed.
Earlier on Thursday, Chinese President Xi Jinping called for a concerted effort by global institutions such as the United Nations and the WTO to fight unilateralism and protectionism.
Xi, who leads the world's second-biggest economy, also called for dialogue to settle disputes on global trade, underlining remarks he made at the opening of the summit the previous day.
"We must work together ... to safeguard the rule-based multilateral trading regime, promote trade and investment, globalisation and facilitation, and reject protectionism outright," Xi said.
On Wednesday, Xi said there would be no winner in a global trade war.
Russian President Vladimir Putin called for more trade within the BRICS bloc.
"We should work to reduce administrative barriers to stimulate trade between our countries," Putin said.
Indian Prime Minister Narendra Modi called for the bloc's members to harness technology to develop their economies.
A handful of protesters gathered near the conference hall where the summit was being held. Their leader, activist Trevor Ngwane, said "none of these heads of state speak for the working class or the poor".
He handed a list of complaints to South African Public Works Minister Thilas Nxesi, who said the BRICS forum would help attract investment and create jobs."The forum must not be seen as if it is for the rich or the bourgeoisie," he said.