About 2.75 billion passengers will take flights in 2011, an increase of 29 per cent on the total passenger traffic in 2006, industry body IATA says.

The Geneva-based International Air Transport Association said the number of travellers taking cross-border flights would increase to 980 million from 760 million in the next five years. Annual growth would average 5.1 per cent.

On domestic routes, passenger demand is expected to hit 1.77 billion by 2011, compared with the 1.37 billion who flew in 2006, due in part to expanded flight traffic inside large countries such as India and China.

"The numbers show that the world wants to fly and it needs to fly," IATA director general Giovanni Bisignani told a conference in Damascus, where the forecast was released.

Mr Bisignani said the increasing demand for air travel - targeted by many environmentalists as a key source of carbon emissions causing global warming - provided the industry with "an opportunity for sound investment in a green future".

He warned that a failure by governments to plan for infrastructure improvements to meet the growing demand and to solve air traffic control problems would "have an environmental cost with inefficient use of air space and delays".

IATA, which represents some 240 companies operating 94 per cent of international scheduled air traffic, opposes eco-taxes on airlines and says the industry is tackling its carbon emissions with investment in new technology.

Its forecast shows that economic growth in India, China and Vietnam will drive domestic and international travel to and from those countries, increasing Asian passenger numbers by an average annual rate of 5.9 per cent.

China's average annual increase for the five years would be 8.8 per cent, India's 8.6 per cent and Vietnam's 7.7 per cent.

In Europe, international passenger demand would grow annually at an average of 5 per cent between 2006 and 2011, driven by a surge in former communist countries.

Among these, Latvia is likely to experience average annual growth over the five years of 12.1 per cent, while in Russia it will hit 9.3 per cent, 9.2 per cent in Poland and 8.8 per cent in Ukraine.

In North America, the maturity of the air travel market - easily the world's largest - and an expected slowing of US economic growth was likely to hold the average passenger increase to 4.2 per cent, IATA said.