The two permanent UNSC members - China and Russia - in a joint statement of the BRICS grouping, said they "support their (India, Brazil and South Africa) aspiration to play a greater role in the UN".
The three countries are in the Security Council but as non-permanent members for a period of two years after their election in January. They are seeking more permanent representation in view of their growing global influence.
The BRICS countries together represent more than 40 percent of the world's population and 20 percent of the global Gross Domestic Product (GDP). The fastest emerging economies are projected to contribute 48 percent to the global economy in the next decade.
"We express our strong commitment to multilateral diplomacy with the United Nations playing the central role in dealing with global challenges and threats," said the joint statement issued after a summit in the Chinese coastal city of Sanya.
The statement, also called the Sanya declaration, was signed by Indian Prime Minister Manmohan Singh, China's Hu Jintao, Brazil's Dilma Rousseff, Russia's Dmitry Medvedev and South Africa's Jacob Zuma. It reaffirmed "the need for a comprehensive reform of the UN, including its Security Council to make it more effective, efficient and representative, so that it can deal with today's global challenges more successfully".
"China and Russia reiterate the importance they attach to the status of India, Brazil and South Africa in international affairs, and understand and support their aspiration to play a greater role in the UN."
Manmohan Singh, in his plenary address to the summit, asked other countries to "join hands in ensuring a peaceful and orderly transformation of the world order that reflects contemporary and emerging realities". "This should be the case whether it is the reform of political and security governance structures in the United Nations or the international financial, monetary or trade system," he said.
Brazil's Rousseff told reporters in a joint address to the media that the reform of the United Nations and its Security Council was "essential". "It is just impossible that we should still remain attached to institutional arrangements that were built in the post-war period," she said.
South Africa's Zuma concurred. "We agreed on the need for reform of the United Nations Security Council system to make it more representative and effective."