"South Africa has joined this meeting. We welcome South Africa. Now BRIC is no longer BRIC but it is BRICS. One ''S'' has been added to it," Mukherjee told reporters.
He is here to participate in the G20 Finance Ministers' meeting.
The next BRICS summit is scheduled to be held in China in April.
South Africa had sought BRIC membership last year and was admitted in the forum in December 2010. It is the largest economy in Africa.