Singh, accompanied by his wife Gursharan Kaur, was accorded a red-carpet welcome at the Brazilian Air Force Base with the presentation of ceremonial Guard of Honour and 21-gun salute.
He was received warmly by Brazilian Defence Minister Nelson Jobin as the military band played national anthems of the host country and India, one by one.
The Prime Minister reached here from Washington on the second leg of his eight-nation tour.
The two Summits will discuss global economic crisis besides ways to enhance cooperation among the member countries of the two groupings.
At the 2nd BRIC Summit, Iran's nuclear issue and the controversy surrounding it will also be discussed under the grouping's format by Singh, Russian President Dmitry Medvedev, Chinese President Hu Jintao and Brazilian President Lula da Silva. This will be the first time that Iran will be part of focussed agenda of the grouping.
BRIC is a significant grouping comprising two of the world's leading energy producers -- Russia and China and top energy consumers -- India and China, which officials say forms the basis for natural synergy.
In the BRIC format, Foreign Ministers of the four countries have been meeting regularly on the sidelines of international conferences, including the UN General Assembly.
The BRIC countries, representing 40 per cent of the global population, are among the largest and fastest growing economies with rich human and material resources. They represent the future of the global economic landscape.
With a similarity of views on several issues like climate change and reform of global institutions, including the UN, the four countries have been fine-tuning their collective approaches to these issues.
In the IBSA format too, India, Brazil and South Africa, the three fastest growing economies of three continents, have been evolving common and coordinated approaches to the challenges like global economic crisis and climate change besides pushing efforts to enhance cooperation among themselves.
After the IBSA Summit on Friday, India, Brazil and South Africa are expected to sign two trilateral MoUs. These are in the areas of solar energy and science and technology.
An MoU in the field of sport is also likely to be inked.
"These groupings reflect the growing role of emerging economies in shaping the global economic order," the Prime Minister had said in a statement before leaving on his two-nation tour.
He said the IBSA process has come of age as it today encompasses a wide range of activities which supplement the excellent bilateral relations that India enjoys with each of these countries.
"Our coordination on important international issues has expanded, and our trilateral cooperation is beginning to bear fruit in many sectors," the Prime Minister had said.
"We have a high stake in the revival of the global economy, an open trading system, energy security, combating climate change and addressing non-traditional threats to international security," he said.
Singh will hold bilateral meetings with the Chinese President and Russian President during his stay here.
Ahead of his meeting with Hu, Singh said in Washington that India and China were working very hard to find a "practical" and "pragmatic" solution to the boundary question and it would "take time" to get resolved.
"Well we have the border problem and that problem has to be resolved. We are working very hard to find to have a practical, pragmatic solution to that problem," he said at a press conference when asked about relations between India and China.
Noting that both countries "recognise that it would take time", he said both the nations have agreed that pending the resolution of the border issues, peace and tranquility should be maintained along the Line of Actual Control and by and large that situation prevails on the ground.
On the overall Sino-India relations, he said the economic content of the relationship has increased significantly, with China today being India's largest trading partner.
There are large Chinese investments in our country and there are large Indian investments in China. "On the economic front the relationship is moving in the right direction," he said.
On multilateral issues, he said, there was a recognition in China that there was a similarity of approach between the two countries and they can gain by working together.
In this context, he referred to the Copenhagen conference on climate change last December during which India and China worked closely to block developed nations from imposing their agenda.
