Kolkata, Feb 15 (IANS) Underlining that Asia is playing a very important role in global economic restructuring, Asian Development Bank (ADB) managing director general Rajat M. Nag said Monday the continent's contribution to the global economy is increasing.

"Asia's share in global economy was 18 percent in 1980, it became 35 percent in 2009 and in 2050 it will be about 60 percent," Nag said while speaking at an interactive session on "South-East Asia Economic Integration", organised by the Indian Chamber of Commerce (ICC) here.

"There is global rebalancing and rise of Asia. The North American economy will shrink," he said.

Stating that there was already a rise of the middle class in Asia, he said after 40 years, India and China would possess about 55 percent of the total middle class in the world.

Asia would be huge market in the future as the continent will add about two billion people by 2050, he added.

"Integrated production, macro-economic consolidation and making growth sustainable will be the key for economic growth," the official of the Manila-based bank said.

Nag, however, said the process of South Asia's economic integration had been very slow.

The proposed Trans-Asian Railway, with sections through northeast India, Bangladesh and Myanmar, was very essential for economic cooperation and integration, he said.

Stating that India's northeastern region was the gateway to East Asia, Nag said India's "Look East" policy could not stand without developing infrastructure in the northeast region.

He also emphasised the need of the current and proposed Asian highways with sections through India's northeast region, Bangladesh and Myanmar.