The two Ambani brothers -- Mukesh and Anil -- are India's richest billionaires, having displaced Azim Premji, founder-chairman of Wipro.

This was seen in a quick study by the Business Standard Research Bureau.

Among other changes in the top five billionaires' list, Zee Telefilms promoter Subhash Chandra has slipped from fourth position in 2002 to eighth, swapping places with Sunil Bharti Mittal of Bharti Tele-Ventures.

The study is based on the average value of stocks held by the Ambani and Premji families in May 2003.

The Ambanis, with average net worth of Rs 17,552 crore (Rs 175.52 billion), topped the BS Billionaire rankings in May.

Premji is now ranked second with a net worth of Rs 17,007 crore (Rs 170.07 billion).

The Wipro chairman, who occupied the top slot for four consecutive years after the Business Standard Research Bureau started compiling the annual BS Billionaire list, saw his net worth eroded by Rs 14,405 crore (Rs 144.05 billion) in May 2003.

In December 2002, at the time of the last compilation, Premji was worth Rs 31,412 crore (Rs 314.12 billion).

The erosion in his net worth started in December 2002 but the drop was sharpest in April and May. The Wipro stock came in for a sustained bear assault after Infosys Technologies posted a poor profit guidance on April 10, 2003.

The net worth of the Ambani family did not increase since December 2002. In fact, it dropped by Rs 1,311 crore (Rs 13.11 billion), from Rs 18,863 crore (Rs 188.63 billion) at the end of December 2002 to Rs 17,552 crore (Rs 175.52 billion) in May 2003.

But the brothers have become the richest Indians primarily because the market capitalisation of Wipro declined.

The Shiv Nadar Group continues at the third spot though its net worth declined further -- from Rs 4,576 crore (Rs 45.76 billion) in December 2002 to Rs 3,309 crore (Rs 33.09 billion) in May.

Now at number four, Mittal recorded a sharp climb in his net worth since the last listing in December 2002 as improved results of his group's listed company Bharti Tele-Ventures in the fourth quarter of 2003 lifted the stock price.

His net worth increased from Rs 2,055 crore (Rs 20.55 billion) to Rs 3,013 crore (Rs 30.13 billion).

Kumar Mangalam Birla of the Aditya Birla Group continues at fifth place even though his net worth increased to Rs 2,436 crore (Rs 24.36 billion) in May from Rs 2,136 crore (Rs 21.36 billion) in December 2002.

Chandra slipped to eighth position, his net worth having eroded to Rs 1,872 crore (Rs 18.72 billion) in May from Rs 2,388 crore (Rs 23.88 billion) in December 2002.