As economic downturn continues to grip the United States, as many as 100,000 highly skilled Indians -- and as many Chinese -- may return home over next three to five years, which will boost the economies and competitiveness of both the emerging Asian nations.

The reverse immigration could end up as a big loss to the US, which has so far relied heavily on the immigrants to give it a technological edge over the rest of the world, according to a study conducted by Indian-American Vivek Wadhwa and released by the Ewing Marion Kauffman Foundation.

The majority of these Western-educated, skilled and talented young Indian and Chinese professionals are planning to start new ventures, says the report released on Monday.

Much before the American economic slowdown, a large number of these professionals had already begun returning home lured apparently by prospects of a better future back home.

It also indicates that placing limits on foreign workers in the US is not the answer to its rising unemployment rate and may undermine efforts to spur technological innovation.

"A substantial number of highly skilled immigrants have started returning to their home countries in recent years, draining a key source of brain power and innovation," said Robert Litan, vice president of Research and Policy at the Kauffman Foundation.

Based on a six month survey of 1,203 Indian and Chinese who went back home, the report finds though restrictive immigration policies caused some returnees to depart the US, the most significant factors in the decision to return home were career opportunities, family ties, and quality of life.

"There are no hard numbers available on how many have returned, but anecdotal evidence shows that this is in the tens of thousands," said Wadhwa, executive-in-residence for Pratt School of Engineering at Duke University.

Wadhwa is also a fellow at the Labour and Work life Programme at Harvard Law School and is a BusinessWeek columnist.

"With the economic downturn, my guess is that we'll have over 100,000 Indians and as many Chinese return home over the next 3-5 years. This flood of western educated and skilled talent will greatly boost the economies of India and China and strengthen their competitiveness," he said.

India is already becoming a global hub for R&D. This will allow it to branch into many new areas and will accelerate the trend, Wadhwa said.

The report reveals that family considerations are strong magnets pulling immigrants back to their home countries. Care for aging parents was considered by 89.4 per cent of Indians and 79.1 per cent of Chinese respondents to be much better in their home countries, says the 24-page report.