Brazil, India and South Africa are working to set up a free trade area they hope will eventually take in the continents they represent.
The three nations hope to boost their bargaining power at the WTO
The three made the pact at talks ahead of an informal World Trade Organization (WTO) meeting in Rio de Janeiro.
The action is on a separate track from the WTO's continuing efforts to free trade between rich and poor nations.
"The final objective of our three countries is a free trade agreement," India's external affairs minister said.
Anand Sharma added that the group held "immense trade perspectives".
The trio - known as IBSA and part of the G20 group of developing nations - has been frustrated by the WTO's lack of progress at breaking down trade barriers.
As a result, on Thursday, they agreed to strengthen their bargaining power at the WTO by boosting their trade links.
Over the past two years, Brazil's trade with India has surged 170%, while its trade with South Africa has risen 86%.
And if a formal alliance is agreed, Brazilian foreign minister Celso Amorim expects trade to surge.
"The aim here is to come to a free trade agreement," he said.
"With a trilateral treaty, trade would multiply. It isn't unthinkable to dream of $14bn to $15bn in a few years' time."
Mr Amorim is also currently working to persuade South America's trade bloc, Mercosur, to expand its trade agreements to take in India and South Africa.