Companies such as RSP Architects, CPG Group and JTC Corp's Jurong International are sitting on projects totalling more than 500 million sq ft of floor space.

These include a 80ha township in Amritsar designed by Jurong, a 1 million sq ft IT park designed by RSP Architects in Bangalore and a 13,000ha special economic zone designed by CPG Group in Mundra, Gujarat.

To get a sense of the scale of Singapore's involvement, picture all the commercial space in Singapore's central region, including the malls and office buildings in its downtown core and Orchard Road.

Now multiply all that by four and you get a sense of the business that just one Singapore design company - RSP Architects - is handling in India.

Jurong has about half that much. Even smaller players, such as CPG, are incredibly busy. CPG has at least 30 million sq ft of projects completed or under construction.

"What we are seeing is the tip of the iceberg that is to surface in the next 10 to 15 years," said Gopi Bhawnani, managing director of RSP (India).

"In the long run, a lot more is going to be happening. China has gone through enormous growth; in India, the infrastructure story is just beginning."

In some places such as Hyderabad in the south, almost all the significant projects in the city appear to be in the hands of Singapore architects.

India is the middle of an unprecedented property boom, thanks in part to new rules in 2005 that permit foreign investment in the construction industry.

According to some estimates, some US$45 billion worth of projects are under construction across India, more than three-quarters of it residential.

A full decade after Bangalore's International Tech Park opened, showcasing Singapore's strengths in infrastructure, design companies from the island are sitting on so much business that they are sometimes said to turn away clients.