With the civil aviation ministry identifying 35 airports for modernisation and nine sites for setting up new airports, more than half a dozen Indian companies are lining up to bid for these projects.

The potential entrants include the Essar Group, Punj Lloyd [Get Quote], Larsen & Toubro, real estate developer Atlanta, Hyderabad-based Nagarjuna Construction and Delhi-based DS Constructions.

The Ambani brothers are also making a pitch as are the Aditya Birla Group and the Tatas along with their partner Changi Airports. Sunil Mittal's Bharti Group is also planning a re-entry following its abortive bid for the modernisation of Delhi and Mumbai airports.

Besides these players, Hyderabad-based GVK Group (which manages the Mumbai international airport) and GMR Group (which manages the Delhi international airport) have decided to explore airport development opportunities in both greenfield and non-metro projects.

Both these developers will have first right of refusal in the proposed airports at Greater Noida and Navi Mumbai.

Currently, most of these potential bidders are searching for partners with experience in airport development.

Punj Lloyd Managing Director Atul Punj said, "At the moment we are talking to some international companies for a tie-up. We could also rope in Indian partners."

A Bharti spokesperson said the company had "no firm plans at the moment," while Essar Group declined to comment specifically, saying it was continuously looking at growth opportunities.

The beeline for airport development is partly because the business offers an attractive real estate opportunity in the form of revenues from non-aeronautical heads like duty-free shops and restaurants.

In many cases, the business also complements the existing businesses -- most of the potential entrants are in real estate in one form or the other.

For instance, Mukesh Ambani's Reliance Industries [Get Quote] finds strong synergies between its two special economic zones being developed at Navi Mumbai and Gurgaon and the Navi Mumbai and Greater Noida airports.

A KPMG report says the key growth drivers for airports would be emergence of budget carriers, cargo growth, favourable government policy, inbound business travel and tourism and outbound passenger travel.

The current revenue pattern of Indian airports shows that 70 per cent of income comes from aeronautical activities and the remaining from non-aeronautical activities, the report adds.