Around 600 million Indians will get the much-cherished Unique Identification Number (UIN) in the next four years, helping implementation of various social welfare schemes.

"About 40,000 to 45,000 people have been enrolled by September 29, 2010. Many more will get the facility in one year and about 600 million in the next four years," Unique Identification Authority of India (UIDAI) chairman Nandan Nilekani said here today.

UID, also known as Aadhaar number, will be helpful in opening a bank account, passport and ration card and many other things, he added.

"The Aadhaar number will be of much help to the people migrating from one place to another," he said.

Stating that out of the 1.8 billion people, about 120 million migrate in search of jobs and other activities, Nilekani said migration affected about 480 million people in the country.

The UID number, therefore, will help people in getting essential services like PDS, bank account, LPG connection and other jobs in new places, he said.

Terming the exercise as the biggest event in the world, Nilekani said that bi-metric system would prevent duplication.

"We have de-duplication exercise which will include or exclude people from the list of people in the UIN list," he added.