By Sunil Raman in Delhi

One of India's most famous businessmen, Ratan Tata, has stepped down as chairman of the Tata group of industries.

Mr Tata is expected to go on playing a significant role at the company as a non-executive chairman for a further five years before relinquishing charge at the age of 70.

Ratan Tata will not nominate his successor

Like the Wallenbergs in Sweden and the Oppenheimers in South Africa, the Tatas interests span much of India's economy.

They founded India's biggest private sector steel company, as well as a truck manufacturer, hotel chain, tea producer, and chemicals and software exporter.

A replacement to head the $10.4bn (£6.5bn)Tata group of companies has yet to be announced.

Climbing the ladder

Rajan Tata was nominated in 1991 by his legendary uncle, JRD Tata to head the Tata group and consolidate its various businesses.

Brought in by JRD because of his "modern mind", the qualified architect and pilot studied at Cornell University before joining the Tatas at the age of 23.

Ratan Tata worked through various companies before being appointed director in charge of Nelco in 1971, chairman of Tata Industries in 1981 and then the chairman of Tata Sons Ltd in 1991.

Tata Indica, the first mass-market car designed and built by an Indian company, was Ratan Tata's brainchild.

But his efforts to start a private airline in partnership with Singapore Airlines failed to take off because of a constant flux in government policies.

Ratan Tata announced earlier that he would not nominate his successor but would leave that to the board of directors.

Insiders believe that his step-brother Noel Tata, one of the current directors, may well succeed him.